Cement admixture and cement composition

ABSTRACT

It is an object of the present invention to provide a cement admixture capable of exhibiting high cement dispersing ability at low addition levels, in particular capable of displaying excellent initial dispersing ability and dispersion retaining ability even in a high water reducing ratio range, and a cement composition in which this admixture is used.  
     A cement admixture comprising  
     two polymers, namely a polymer (A) and a polymer (B), as essential constituents in a ratio of polymer (A) to polymer (B) between 1 to 99/99 to 1% by mass,  
     wherein the polymer (A) is a polymer comprising, as essential constituent units, a constituent unit (I) derived from an unsaturated (poly)alkylene glycol ether monomer (a) and a constituent unit (II) derived from an unsaturated monocarboxylic acid monomer (b) and  
     wherein the constituent units (I) and (II) each accounts for not less than 1% by mass relative to all constituent units but the constituent unit (I) accounts for not more than 50 mole percent relative to all constituent units and,  
     wherein the polymer (B) is an oxyalkylene group- or polyoxyalkylene group- and carboxyl group-containing polymer.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a cement admixture and a cementcomposition comprising the same.

PRIOR ART

[0002] A cement paste prepared by adding water to cement, a mortarprepared by admixing sand, which is a fine aggregate, therewith, and aconcrete prepared by further admixing gravel, which is a coarseaggregate, therewith are used in large amounts in various structuralmaterials and the like. However, with the lapse of time, mortar andconcrete harden because of the progress of the hydration reactionbetween cement and water and, therefore, their workability generallydecreases with the time after addition of water. For securing thedispersing ability of such cement, various cement admixtures have beendeveloped.

[0003] Thus, for example, Japanese Kokoku Publication Sho-59-18338discloses a cement dispersant produced by copolymerization of apolyalkylene glycol mono(meth)acrylate ester monomer and a (meth)acrylicacid monomer. The cement dispersant disclosed in the cited patentspecification has polyalkylene glycol chains, which are nonionichydrophilic groups, and anionic carboxyl groups in each molecule and thehydrophilicity and steric hindrance of the former inhibit the adsorptionof the latter to cement particles and, allegedly, its setting retardingeffect is weak and its dispersing performance is good.

[0004] Japanese Kokai Publication Hei-04-175254 discloses a cementdispersant comprising two kinds of polymer, wherein the first componentis a polyether compound derived from a copolymer of maleic anhydride anda polyalkylene glycol allyl alkyl ether by further monoesterificationwith alkylpolyalkylene glycol and the second component is a salt of apolycarboxylic acid, which is a polymer of (meth)acrylic acid or thelike. Allegedly, the second component polycarboxylic acid saltincorporated in the cement dispersant disclosed in the above-citedpatent specification is first preferentially adsorbed on cementparticles and disperses the cement particles in water and, then, thepolyether compound contained as the first component and slow in rate ofadsorption on cement particles is adsorbed on cement, whereby thedispersing ability of cement can be secured for a long period of time.

[0005] Japanese Kokai Publication Hei-05-345647 also discloses cementdispersant comprising two kinds of polymer, wherein the first componentis a copolymer (a) of maleic anhydride and alkenyl ether with not lessthan 100 moles of an oxyalkylene group added and the second component ispolycarboxylic acid type cement dispersant (b). It is described in thecited patent specification that the component (b) serves to increase thedispersing ability of cement at an early stage and the component (a), inwhich the number of moles of the oxyalkylene group added is not lessthan 100, causes a hydrated layer to be formed around eachpolyoxyalkylene group extending from the copolymer adsorbed on cementparticles and, owing to the resulting steric hindrance, the dispersingability of cement particles is retained for a prolonged period of timeand that an increase in polyether chain length in component (a) resultsin a tendency to increase the slump with time.

[0006] Japanese Kokai Publication Hei-07-267705 discloses a cementdispersant comprising three kinds of polymer, in which the firstcomponent is a copolymer (a) of a polyalkylene glycol mono(meth)acrylatecompound and a (meth)acrylic acid compound, the second component is acopolymer (b) of a polyalkylene glycol mono(meth)allyl ether compoundand maleic anhydride and the third component is a copolymer (c) of apolyalkylene glycol mono(meth)allyl ether compound and a maleicacid-esterified polyalkylene glycol compound. The cited patentspecification describes that the component (a), when used alone,increases the initial flowability of cement but is poor inslump-retaining ability and increases the viscosity of the cementcomposition, that the component (b), when used alone, requires time toincrease the initial flowability and, even when the initial flowabilityis increased by increasing the level of addition thereof, it causesphase separation of the cement composition with time, that the component(c), when used alone, is further poor in cement dispersing ability andthat, therefore, such effects that cannot be obtained by the single useof each of the three components are produced by combinedly using them inspecific proportions. Thus, it is presumed, in the cited specification,that the differences in mechanisms of action on cement among thecomponents are due to the molecular structures of the components and thedifferences in initial flowability increasing effect are due to thehigher rate of adsorption, on cement particles, of the (meth)acrylicacid-based functional group-containing polymer (component a) as comparedwith the maleic acid-based functional group-containing polymers(components b and c). It is further described that the component higherin rate of adsorption is poor in the ability to subsequently retain theflowability.

[0007] Further, Japanese Kokai Publication 2001-19514 also discloses acement dispersant comprising two kinds of polymer, wherein the firstcomponent is a polymer (A) of a polyalkylene glycol mono(meth)acrylatemonomer and a (meth)acrylic acid monomer and the second component is apolymer (B) of a polyalkylene glycol monoalkenyl ether and maleic acid.The cited patent specification describes that when the carboxyl groupcontent and the addition number of moles of the alkylene oxide to attainthe polyalkylene glycol chain length in these polymers are withinrespective specific ranges, the combined use of the polymers can providesuch excellent initial dispersing ability and slump-retaining abilitythat cannot be attained with the conventional products.

[0008] Japanese Kokai Publication 2001-34151 also discloses a cementadmixture comprising two species of copolymers obtained bycopolymerization of two or more species of unsaturated (poly)alkyleneglycol ether monomers having a specific structure and (meth)acrylic acidmonomers. In Example, an unsaturated (poly)alkylene glycol ether monomerwhich contains a terminal alkyl group containing 1 to 3 carbon atoms anda short (poly)alkylene glycol chain, is used. When the unsaturated(poly)alkylene glycol ether monomer contains an alkyl group as aterminal group and a short (poly)alkylene glycol chain for increasingshrinkage decreasing effects of concrete, its hydrophobicity increasesto thereby reduce the dispersing ability of copolymers. In particular,there are no dispersants available for providing cement with sufficientdispersing ability in a high water reducing ratio range.

[0009] Thus, the technique is known in the art which comprisesincorporating a polyalkylene glycol mono(meth)acrylate/(meth)acrylicacid copolymer and a polyalkylene glycol monoalkenyl ether/maleic acidcopolymer combinedly in cement admixtures. At present, however, it isimpossible to secure both sufficient initial dispersing ability anddispersion retaining ability with each other; for the manifestation ofsufficient initial dispersing ability, it is necessary to add thedispersants in large amounts. In particular, there are no dispersantsavailable for providing cement with sufficient dispersing ability anddispersion retaining ability in a high water reducing ratio range.

[0010] In view of the above-mentioned state of the art, it is an objectof the present invention to provide a cement admixture capable ofexhibiting high cement dispersing ability at low addition levels, inparticular capable of displaying excellent initial dispersing abilityand dispersion retaining ability even in a high water reducing ratiorange, and a cement composition in which this admixture is used.

SUMMARY OF THE INVENTION

[0011] As a result of intensive investigations, the present inventorsfound that a mixture comprising a combination of a specific(poly)alkylene glycol alkenyl ether compound obtained by using anunsaturated monocarboxylic acid monomer as an essential comonomerconstituent in lieu of maleic acid that has so far been used, and a(poly)oxyalkylene group- and carboxyl group-containing compound can showexcellent initial dispersing ability and dispersion retaining abilityeven in a high water reducing ratio range. They further found that amixture comprising a combination of a (poly)oxyalkylene group- andcarboxyl group-containing compound and a specific (poly)alkylene glycolalkenyl ether compound obtained by using an unsaturated monocarboxylicacid ester monomer as an essential comonomer constituent can exhibitexcellent dispersion retaining ability with time even in a high waterreducing ratio range. These and other findings have now led tocompletion of the present invention. In the following, the invention isdescribed in detail.

[0012] The present invention includes the following 1) to 14) aspects:

[0013] 1) A cement admixture comprising

[0014] two polymers, namely a polymer (A1) and a polymer (B1), asessential constituents in a ratio of polymer (A1) to polymer (B1)between 1 to 99/99 to 1% by mass,

[0015] wherein the polymer (A1) is a polymer comprising, as essentialconstituent units, a constituent unit (I) derived from an unsaturated(poly)alkylene glycol ether monomer (a1) represented by the generalformula (1):

YO(R¹O)_(m)H  (1)

[0016] wherein Y represents an alkenyl group containing 2 to 8 carbonatoms, the m R¹O groups are the same or different and each R¹Orepresents an oxyalkylene group containing 2 to 18 carbon atoms and m isa mean addition number of moles of the oxyalkylene group and representsa number of 1 to 500,

[0017] and a constituent unit (II) derived from an unsaturatedmonocarboxylic acid monomer (b) and

[0018] wherein the constituent units (I) and (II) each accounts for notless than 1% by mass relative to all constituent units but theconstituent unit (I) accounts for not more than 50 mole percent relativeto all constituent units and,

[0019] wherein the polymer (B1) is an oxyalkylene group- orpolyoxyalkylene group- and carboxyl group-containing polymer.

[0020] 2) A cement admixture comprising

[0021] two polymers, namely a polymer (A2) and a polymer (B2), asessential constituents in a ratio of polymer (A2) to polymer (B2)between 1 to 99/99 to 1% by mass,

[0022] wherein the polymer (A2) is a polymer comprising, as essentialconstituent units, a constituent unit (I′) derived from an unsaturated(poly)alkylene glycol ether monomer (a2) represented by the generalformula (2):

YO(R¹O)_(n)R²  (2)

[0023] wherein Y represents an alkenyl group containing 2 to 8 carbonatoms, the n R¹O groups are the same or different and each R¹Orepresents an oxyalkylene group containing 2 to 18 carbon atoms, R²represents a hydrogen atom or a hydrocarbon group containing 1 to 30carbon atoms and n is a mean addition number of moles of the oxyalkylenegroup and represents a number of 1 to 500,

[0024] a constituent unit (II) derived from an unsaturatedmonocarboxylic acid monomer (b) and a constituent unit (III) derivedfrom an unsaturated monocarboxylic ester monomer (c),

[0025] wherein the constituent units (I′), (II) and (III) each accountsfor not less than 1% by mass relative to all constituent units but theconstituent unit (I′) accounts for not more than 50 mole percentrelative to all constituent units and the sum of the proportions of theconstituent units (II) and (III) is greater than the proportion of theconstituent unit (I′) on the mole ratio basis,

[0026] wherein the polymer (B2) is an oxyalkylene group- orpolyoxyalkylene group- and carboxyl group-containing polymer.

[0027] 3) The cement admixture according to (2),

[0028] wherein the constituent unit (III) derived from an unsaturatedmonocarboxylic acid ester monomer (c) is a constituent unit (IV) derivedfrom a (poly)alkylene glycol mono(meth)acrylic acid ester monomer (d)represented by the general formula (3):

[0029] wherein R³ and R⁴ are the same or different and each represents ahydrogen atom or a methyl group, the p R⁵O groups are the same ordifferent and each R⁵O represent an oxyalkylene group containing 2 to 18carbon atoms, p is a mean addition number of moles of the oxyalkylenegroup and represents a number of 1 to 500, and R⁶ represents a hydrogenatom or a hydrocarbon group containing 1 to 30 carbon atoms,

[0030] or a constituent unit (VI) derived from a hydrophobic unsaturatedmonocarboxylic acid ester monomer (f) represented by the general formula(4):

[0031] wherein R⁷ and R⁸ are the same or different and each represents ahydrogen atom or a methyl group and R⁹ represents a hydrocarbon groupcontaining 1 to 30 carbon atoms.

[0032] 4) A cement admixture comprising

[0033] two polymers, namely a polymer (A3) and a polymer (B3), asessential constituents in a ratio of polymer (A3) to polymer (B3)between 1 to 99/99 to 1% by mass,

[0034] wherein the polymer (A3) is a polymer comprising, as essentialconstituent units, a constituent unit (I′) derived from an unsaturated(poly)alkylene glycol ether monomer (a2) represented by the generalformula (2):

YO(R¹O)_(n)R²  (2)

[0035] wherein Y represents an alkenyl group containing 2 to 8 carbonatoms, the n R¹O groups are the same or different and each R¹Orepresents an oxyalkylene group containing 2 to 18 carbon atoms, R²represents a hydrogen atom or a hydrocarbon group containing 1 to 30carbon atoms and n is a mean addition number of moles of the oxyalkylenegroup and represents a number of 1 to 500,

[0036] and a constituent unit (II) derived from an unsaturatedmonocarboxylic acid monomer (b) and

[0037] wherein the constituent units (I′) and (II) each accounts for notless than 1% by mass relative to all constituent units but theconstituent unit (I′) accounts for not more than 50 mole percentrelative to all constituent units and

[0038] wherein the polymer (B3) is a polymer comprising a constituentunit (IV) derived from a (poly)alkylene glycol mono(meth)acrylic acidester monomer (d) represented by the general formula (3):

[0039] wherein R³ and R⁴ are the same or different and each represents ahydrogen atom or a methyl group, the p R⁵O groups are the same ordifferent and each R⁵O represent an oxyalkylene group containing 2 to 18carbon atoms, p is a mean addition number of moles of the oxyalkylenegroup and represents a number of 1 to 500, and R⁶ represents a hydrogenatom or a hydrocarbon group containing 1 to 30 carbon atoms,

[0040] and a constituent unit (II) derived from an unsaturatedmonocarboxylic acid monomer (b).

[0041] 5) A cement admixture comprising

[0042] two polymers, namely a polymer (A3) and a polymer (B4), asessential constituents in a ratio of polymer (A3) to polymer (B4)between 1 to 99/99 to 1% by mass,

[0043] wherein the polymer (A3) is a polymer comprising, as essentialconstituent units, a constituent unit (I′) derived from an unsaturated(poly)alkylene glycol ether monomer (a2) represented by the generalformula (2):

YO(R¹O)_(n)R²  (2)

[0044] wherein Y represents an alkenyl group containing 2 to 8 carbonatoms, the n R¹O groups are the same or different and each R¹Orepresents an oxyalkylene group containing 2 to 18 carbon atoms, R²represents a hydrogen atom or a hydrocarbon group containing 1 to 30carbon atoms and n is a mean addition number of moles of the oxyalkylenegroup and represents a number of 1 to 500,

[0045] and a constituent unit (II) derived from an unsaturatedmonocarboxylic acid monomer (b),

[0046] wherein the constituent units (I′) and (II) each accounts for notless than 1% by mass relative to all constituent units but theconstituent unit (I′) accounts for not more than 50 mole percentrelative to all constituent units,

[0047] wherein the polymer (B4) is a polymer comprising a constituentunit (I′) derived from an unsaturated (poly)alkylene glycol ethermonomer (a2) represented by the general formula (2) and a constituentunit (V) derived from an unsaturated dicarboxylic acid monomer (e).

[0048] 6) A cement admixture comprising two polymers, namely a polymer(G) and a polymer (B5), as essential constituents in a ratio of polymer(G) to polymer (B5) between 1 to 99/99 to 1% by mass,

[0049] wherein the polymer (B5) is an oxyalkylene or polyoxyalkylenegroup- and carboxyl group-containing polymer and

[0050] the polymer (G) is a polymer comprising, as essential constituentunits, a constituent unit (I′) derived from an unsaturated(poly)alkylene glycol ether monomer (a2) represented by the generalformula (2):

YO(R¹O)_(n)R²  (2)

[0051] wherein Y represents an alkenyl group containing 2 to 8 carbonatoms, the n R¹O groups are the same or different and each R¹Orepresents an oxyalkylene group containing 2 to 18 carbon atoms, R²represents a hydrogen atom or a hydrocarbon group containing 1 to 30carbon atoms and n is the mean addition number of moles of theoxyalkylene group and represents a number of 1 to 500,

[0052] and a constituent unit (III) derived from an unsaturatedmonocarboxylic acid ester monomer (c),

[0053] wherein the constituent units (I′) and (III) each accounts fornot less than 1% by mass relative to all constituent units but theconstituent unit (I′) accounts for not more than 50 mole percentrelative to all constituent units.

[0054] 7) The cement admixture according to 6),

[0055] wherein the number of milliequivalents of carboxyl groupscontained in each gram of the polymer (G) as determined on theunneutralized basis is 0 to 0.8 meq/g.

[0056] 8) The cement admixture according to 6) or 7),

[0057] wherein the polymer (B5) is a polymer comprising, as essentialconstituent units, a constituent unit (IV) derived from a (poly)alkyleneglycol mono(meth)acrylic acid ester monomer (d) represented by thegeneral formula (3):

[0058] wherein R³ and R⁴ are the same or different and each represents ahydrogen atom or a methyl group, the p R⁵O groups are the same ordifferent and each R⁵O represent an oxyalkylene group containing 2 to 18carbon atoms, p is a mean addition number of moles of the oxyalkylenegroup and represents a number of 1 to 500 and R⁶ represents a hydrogenatom or a hydrocarbon group containing 1 to 30 carbon atoms,

[0059] and a constituent unit (II)derived from an unsaturatedmonocarboxylic acid monomer (b).

[0060] 9) The cement admixture according to 6) or 7),

[0061] wherein the polymer (B5) is a polymer comprising, as essentialconstituent units, the constituent unit (I′) derived from an unsaturated(poly)alkylene glycol ether monomer (a2) represented by the generalformula (2) and a constituent unit (V) derived from an unsaturateddicarboxylic acid monomer (e).

[0062] 10) The cement admixture according to any of 6) to 9),

[0063] wherein the constituent unit (III) derived from an unsaturatedmonocarboxylic acid ester monomer (c) is a constituent unit (IV) derivedfrom a (poly)alkylene glycol mono(meth)acrylic acid ester monomer (d) ora constituent unit (VI) derived from a hydrophobic unsaturatedmonocarboxylic acid ester monomer (f) represented by the general formula(4):

[0064] wherein R⁷ and R⁸ are the same or different and each represents ahydrogen atom or a methyl group and R⁹ represents a hydrocarbon groupcontaining 1 to 30 carbon atoms.

[0065] 11) The cement admixture according to any 1) to 10) comprising

[0066] a non-polymerizable (poly)alkylene glycol (P) not containing analkenyl group.

[0067] 12) The cement admixture according to 1) comprising

[0068] the unsaturated (poly)alkylene glycol ether monomer (a1).

[0069] 13) The cement admixture according to any of 2) to 11) comprising

[0070] the unsaturated (poly)alkylene glycol ether monomer (a2).

[0071] 14) A cement composition comprising,

[0072] as essential constituents, the cement admixture according to anyof 1) to 13), cement and water.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0073] The cement admixtures according to the present invention compriserespectively, as essential constituents, the two kinds of polymer, (1)polymer (A1) and polymer (B1), (2) polymer (A2) and polymer (B2), (3)polymer (A3) and polymer (B3), (4) polymer (A3) and polymer (B4), or (5)polymer (G) and polymer (B5). In this description, these cementadmixtures are represented by the following words, namely cementadmixture (1), cement admixture (2), cement admixture (3), cementadmixture (4) and cement admixture (5), respectively. The cementadmixture (1) can be obtained by mixing together the two polymers (A1)and (B1) separately synthesized. The cement admixture (2) can beobtained by mixing together the two polymers (A2) and (B2) separatelysynthesized. The cement admixture (3) can be obtained by mixing togetherthe two polymers (A3) and (B3) separately synthesized. The cementadmixture (4) can be obtained by mixing together the two polymers (A3)and (B4) separately synthesized. The cement admixture (5) can beobtained by mixing together the two polymers (G) and (B5) separatelysynthesized.

[0074] These polymers are respectively described below.

[0075] The polymer (A1), (A2), and (A3) of the present invention, arepolymers comprising, as essential constituent units, an unsaturated(poly)alkylene glycol ether monomer-derived constituent unit and anunsaturated monocarboxylic acid monomer-derived constituent unit.Further, in this description, polymer (A) means all of the polymer (A1),(A2), and (A3).

[0076] The polymer (A1) is a polymer comprising, as essentialconstituent units, the constituent unit (I) derived from an unsaturated(poly)alkylene glycol ether monomer (a1) represented by the abovegeneral formula (1) and the constituent unit (II) derived from anunsaturated monocarboxylic acid monomer (b). Although the polymer (A1)is a polymer comprising the constituent units (I) and (II) as essentialconstituents, it may further contain another or other copolymerizablemonomer-derived constituent units. These constituent units in polymer(A1) each may comprise one single species or two or more species.

[0077] It is necessary that, in the above the polymer (A1), theconstituent units (I) and (II) each account for at least 1% by massrelative to all constituent units and the proportion of the constituentunit (I) be not more than 50 mole percent relative to all constituentunits. When the proportion of constituent unit (I) is less than 1% bymass, the content of the unsaturated (poly)alkylene glycol ether monomer(a)-derived oxyalkylene group in the polymer (A1) is too low and, whenthe proportion of constituent unit (II) is less than 1% by mass, thecontent of the unsaturated monocarboxylic acid monomer (b)-derivedcarboxyl group in the polymer (A1) is too low, so that, in either case,no sufficient dispersing ability can be exhibited. On the other hand,for obtaining the polymer (A1) with high dispersing ability in highyields, it is important that the proportion of the constituent unit (I)should be not more than 50 mole percent relative to all constituentunits, since the polymerizability of the unsaturated (poly)alkyleneglycol ether monomer (a1) is low. While it is necessary that theproportion of the constituent unit (I) be at least 1% by mass relativeto 100% by mass of all constituent units, the proportion is preferablynot less than 5% by mass, more preferably not less than 10% by mass,still more preferably not less than 20% by mass, most preferably notless than 40% by mass. The total content (% by mass) of the constituentunits (I) and (II) in the polymer (A1) is preferably 50 to 100% by mass,more preferably 70 to 100% by mass, relative to the whole polymer (A1).

[0078] While it is necessary that, in the above polymer (A1), thecarboxyl group-containing constituent unit (II) derived from anunsaturated monocarboxylic acid monomer (b) accounts for at least 1% bymass relative to all constituent units, it is preferred that the numberof milliequivalents of carboxyl groups contained in each gram of polymer(A1) as determined on the unneutralized basis be 0.2 to 5.0 meq/g. It isthus preferred that the proportion of each constituent unit constitutingthe polymer (A1) be selected so that the number of milliequivalents ofcarboxyl groups in the polymer (A1) amount to a value within the aboverange. The number of milliequivalents of carboxyl groups is morepreferably 0.3 to 4.5 meq/g, still more preferably 0.3 to 4.0 meq/g, inparticular 0.4 to 3.5 meq/g, most preferably 0.4 to 3.0 meq/g. The upperlimit to the content of constituent unit (II) can be selected in amanner such that the number of milliequivalents of carboxyl groupscontained in the polymer (A1) as determined on the unneutralized basismay be within the above range.

[0079] The term “number of milliequivalents of carboxyl groups containedin each gram of polymer (A1) (meq/g) as determined on the unneutralizedbasis” is used herein to include the case where the polymer (A1) is in asalt form. The methods of calculation are shown below for the case whereit occurs as an acid and for the case where it occurs as a salt. While,in the following calculations, the constituent unit (II)-derivedcarboxyl groups alone are exemplified, another carboxyl group-containingconstituent unit, for example the constituent unit (V) derived from anunsaturated dicarboxylic acid monomer (e), which is to be mentionedlater herein, if contained in the polymer, this must be taken intoconsideration in calculating the number of milliequivalents of carboxylgroups.

[0080] (Calculation Example 1): When a copolymer with a monomer(a1)/monomer (b) content ratio of 90/10 (% by mass) is obtained by usingacrylic acid as monomer (b), the number of milliequivalents of monomer(b)-derived carboxyl groups per gram of the above polymer as determinedon the unneutralized basis is (0.1/72)×1,000=1.39 (meq/g), since themolecular weight of acrylic acid is 72.

[0081] (Calculation Example 2): When a copolymer with a monomer(a1)/monomer (b) content ratio of 80/20 (% by mass) is obtained by usingsodium acrylate as monomer (b), the number of milliequivalents ofmonomer (b)-derived carboxyl groups per gram of the above polymer asdetermined on the unneutralized basis is(0.2×72/94)/(0.8+0.2×72/94)/72×1,000=2.23 (meq/g), since the molecularweight of sodium acrylate is 94 and that of acrylic acid is 72. Whenacrylic acid is used in carrying out polymerization and, afterpolymerization, the acrylic acid-derived carboxylic groups arecompletely neutralized with sodium hydroxide, the same result as in thiscalculation example is obtained.

[0082] In addition to the monomer-based method of calculating the numberof milliequivalents of carboxyl groups contained in each gram of polymer(A1) (meq/g) as determined on the unneutralized basis, as mentionedabove, the number can also be calculated by measuring the acid value ofthe above polymer while taking into consideration the counter ionspecies relative to the carboxyl groups in the polymer.

[0083] As the above polymer (A1), the polymer (C) may also be used,which comprises, as essential constituent units, the constituent unit(I) derived from an unsaturated (poly)alkylene glycol ether monomer (a1)represented by the above general formula (1), the constituent unit (II)derived from an unsaturated monocarboxylic acid monomer (b) and theconstituent unit (III) derived from an unsaturated monocarboxylic acidester monomer (c). The cement admixture in which the above polymer (A1)is such polymer (C) is one of the preferred embodiments of the presentinvention. While the polymer (C) is a polymer comprising the constituentunits (I), (II) and (III) as essential constituent units, it may furthercomprise another or other copolymerizable monomers-derived otherconstituent units. These constituent units of the polymer (C) each maycomprise one single species or two or more species.

[0084] Referring to the above polymer (C), it is necessary that theconstituent units (I), (II) and (III) each accounts for not less than 1%by mass relative to all constituent units and that the sum of theproportions of the constituent units (II) and (III) is greater than theproportion of the constituent unit (I) on the mole ratio basis. When theproportion of constituent unit (I) is less than 1% by mass, the contentof an unsaturated (poly)alkylene glycol ether monomer (a1)-derivedoxyalkylene groups in the polymer (C) is too low. When the proportion ofconstituent unit (II) is less than 1% by mass, the content of anunsaturated monocarboxylic acid monomer (b)-derived carboxyl groups inthe polymer (C) is too low and, when the proportion of constituent unit(III) is less than 1% by mass, the content of the unsaturatedmonocarboxylic acid ester monomer (c)-derived substituents in thepolymer (C) is too low. In each case, any satisfactory level ofdispersing ability cannot be attained. As for the mutual proportions ofthe constituent units, it is necessary, for obtaining the polymer (C)with high dispersing ability in high yields, that the sum of theproportions of the constituent units (II) and (III) is greater than theproportion of the constituent unit (I) on the mole ratio basis, sincethe unsaturated (poly)alkylene glycol ether monomer (a1) is low inpolymerizability. The proportion of constituent unit (I) relative to100% by mass of all constituent units is required to be not less than 1%by mass and is preferably not less than 5% by mass, more preferably notless than 10% by mass, still more preferably not less than 20% by mass,most preferably not less than 40% by mass. The proportion of constituent(III) relative to 100% by mass of all constituent units is required tobe not less than 1% by mass and is preferably not less than 2% by mass,more preferably not less than 3% by mass, still more preferably not lessthan 4% by mass, most preferably not less than 5% by mass. The totalcontent (% by mass) of the constituents (I), (II) and (III) in thepolymer (C) is preferably 50 to 100% by mass, more preferably 70 to 100%by mass, relative to the polymer (C) as a whole.

[0085] In the above polymer (C), like in the polymer (A1), it isnecessary that the constituent unit (II) containing the unsaturatedmonocarboxylic acid monomer (b)-derived carboxyl group account for atleast 1% by mass relative to all constituent units and, further, it ispreferred that the number of milliequivalents of carboxyl groupscontained in each gram of polymer (C) as determined on the unneutralizedbasis be 0.2 to 5.0 meq/g, hence it is preferred that the content ratiosof the polymer (C)-constituting constituent units be selected so thatthe number of milliequivalents of carboxyl groups in the polymer (C) mayfall within the above range. For attaining a high level ofdispersion-retaining ability, in particular, it is more preferable thatthe above-mentioned number of milliequivalents of carboxyl groups be 0.2to 2.0 meq/g, still more preferably 0.2 to 1.5 meq/g, in particular 0.2to 1.0 meq/g, most preferably 0.2 to 0.8 meq/g. The upper limit to thecontent of constituent unit (II) can be selected so that the number ofmilliequivalents of carboxyl groups contained in the polymer (C) asdetermined on the unneutralized basis may be within the above range. Thenumber of milliequivalents of carboxyl groups per gram of polymer (C)can be calculated in the same manner as mentioned above referring to thepolymer (A1).

[0086] Since the polymer (A1) and polymer (C) may contain anothercarboxyl-containing constituent unit, for example the above-mentionedconstituent unit (V) derived from an unsaturated dicarboxylic acidmonomer (e), in addition to the carboxyl-containing constituent unit(II) derived from an unsaturated monocarboxylic acid monomer (b), thenumber of milliequivalents of carboxyl groups (meq/g) contained in thepolymer (A1) and polymer (C) is not limited to the case where itoriginates in the constituent unit (II) alone.

[0087] The above polymer (A1) can be produced by copolymerizing amonomer component comprising, as essential constituents, an unsaturated(poly)alkylene glycol ether monomer (a1), which provides the constituentunit (I), and an unsaturated monocarboxylic acid monomer (b), whichprovides the constituent unit (II). The method of production thereof isnot limited to this method but may comprise, for example, using amonomer before alkylene oxide addition, namely methallyl alcohol or alike unsaturated alcohol, in lieu of monomer (a1), copolymerizing thesame with a monomer (b) in the presence of a polymerization initiator(where necessary, copolymerizing these monomers with a furthermonomer(s) copolymerizable therewith) and, thereafter, causing 1 to 500moles, on average, of an alkylene oxide to add to the resultingcopolymer. In the same manner, the polymer (C) can be produced bycopolymerizing a monomer component comprising, as essentialconstituents, an unsaturated (poly)alkylene glycol ether monomer (a1),which provides the constituent unit (I), an unsaturated monocarboxylicacid monomer (b), which provides the constituent unit (II), and anunsaturated monocarboxylic acid ester monomer (c), which provides theconstituent unit (III). The method of production is not limited to thisbut may comprise copolymerizing a monomer component prior to, orwithout, alkylene oxide addition and, thereafter, causing an alkyleneoxide to add to the resulting copolymer.

[0088] The above-mentioned polymer (A2) is a polymer comprising, asessential constituent units, the constituent unit (I′) derived from anunsaturated (poly)alkylene glycol ether monomer (a2) represented by theabove general formula (2), the constituent unit (II) derived from anunsaturated monocarboxylic acid monomer (b) and the constituent unit(III) derived from an unsaturated monocarboxylic ester monomer (c),wherein the constituent units (I′), (II) and (III) each accounts for notless than 1% by mass relative to all constituent units but theconstituent unit (I′) accounts for not more than 50 mole percentrelative to all constituent units and the sum of the proportions of theconstituent units (II) and (III) is greater than the proportion of theconstituent unit (I′) on the mole ratio basis. This polymer (A2) is theabove polymer (C), wherein the constituent unit (I) derived from anunsaturated (poly)alkylene glycol ether monomer (a1) in the polymer (C)is the constituent unit (I′) derived from an unsaturated (poly)alkyleneglycol ether monomer (a2).

[0089] The number of milliequivalents of carboxyl groups contained ineach gram of polymer (A2) (meq/g) as determined on the unneutralizedbasis and the preferred range thereof are the same as described for thepolymer (C). Further, in the preferred embodiment of the polymer (A2),the R² of the unsaturated (poly)alkylene glycol ether monomer (a2) is ahydrogen atom. Namely, the polymer (A2) is preferably the polymer (C).

[0090] The above-mentioned polymer (A3) is a polymer comprising, asessential constituent units, the constituent unit (I′) derived from anunsaturated (poly)alkylene glycol ether monomer (a2) represented by theabove general formula (2) and the constituent unit (II) derived from anunsaturated monocarboxylic acid monomer (b), wherein the constituentunits (I′) and (II) each accounts for not less than 1% by mass relativeto all constituent units but the constituent unit (I′) accounts for notmore than 50 mole percent relative to all constituent units. Thispolymer (A3) is the above polymer (A1), wherein the constituent unit (I)derived from an unsaturated (poly)alkylene glycol ether monomer (a1) inthe polymer (A1) is the constituent unit (I′) derived from anunsaturated (poly)alkylene glycol ether monomer (a2).

[0091] The number of milliequivalents of carboxyl groups contained ineach gram of polymer (A3) (meq/g) as determined on the unneutralizedbasis and the preferred range thereof are the same as described for thepolymer (A1). Further, in the preferred embodiment of the polymer (A3),the polymer (A3) is preferably the polymer (A2), and more preferably thepolymer (C), wherein the R² of the unsaturated (poly)alkylene glycolether monomer (a2) is a hydrogen atom.

[0092] The above-mentioned polymer (G) is a polymer comprising, asessential constituent units, the constituent unit (I′) derived from anunsaturated (poly)alkylene glycol ether monomer (a2) represented by theabove general formula (2) and the constituent unit (III) derived from anunsaturated monocarboxylic acid ester monomer (c).

[0093] In the above polymer (G), it is necessary that the constituentunits (I′) and (III) each account for at least 1% by mass relative toall constituent units and that the constituent unit (I′) account for notmore than 50 mole percent relative to all constituent units. When theproportion of the constituent unit (I′) is less than 1% by mass, theunsaturated (poly)alkylene glycol ether monomer (a2)-derived oxyalkylenegroup content in the polymer (G) is too low and, when the proportion ofthe constituent unit (III) is less than 1% by mass, the unsaturatedmonocarboxylic acid ester monomer (c)-derived carboxylic acid estercontent in the polymer (G) is too low, so that the polymer cannotproduce any sufficient dispersion retaining ability. On the other hand,since the unsaturated (poly)alkylene glycol ether monomer (a2) is low inpolymerizability, it is important, for obtaining the polymer (G) withhigh dispersion retaining ability in high yields, that the proportion ofconstituent unit (I′) be not more than 50 mole percent relative to allconstituent units. While the proportion of constituent unit (I′) isrequired to be not less than 1% by mass relative to all constituentunits, the proportion is preferably not less than 5% by mass, morepreferably not less than 10% by mass, still more preferably not lessthan 20% by mass, in particular not less than 40% by mass. Theproportion of constituent unit (III) is required to be not less than 1%by mass relative to all constituent units but is preferably not lessthan 2% by mass, more preferably not less than 5% by mass, still morepreferably not less than 10% by mass, in particular not less than 20% bymass. The total content (% by mass) of the constituent units (I′) and(III) in the polymer (G) is preferably 50 to 100% by mass, morepreferably 70 to 100% by mass, of the polymer (G) as a whole.

[0094] The above polymer (G) is a polymer comprising the constituentunits (I′) and (III) as essential constituent units, and may comprise afurther copolymerizable monomer-derived constituent unit or units. Theseconstituent units in the polymer (G) each may comprise one singlespecies or two or more species. Therefore, the polymer (G) may comprisea carboxyl group-containing constituent unit in addition to theconstituent units (I′) and (III). The carboxyl group-containingconstituent unit may be the constituent unit (II) derived from anunsaturated monocarboxylic acid monomer (b), the constituent unit (V)derived from an unsaturated dicarboxylic acid monomer (e) or anothercarboxyl group-containing constituent unit.

[0095] In the practice of the present invention, it is preferred thatthe number of milliequivalents of carboxyl groups contained in each gramof the above polymer (G) as determined on the unneutralized basis be 0to 0.8 meq/g, hence it is preferred that the content ratios of thepolymer (G)-constituting constituent units be selected so that thenumber of milliequivalents of carboxyl groups in the polymer (G) mayfall within such range. For attaining a high level of dispersionretaining ability, in particular, it is more preferable that theabove-mentioned number of milliequivalents of carboxyl groups be 0 to0.7 meq/g, still more preferably 0 to 0.6 meq/g, further more preferably0 to 0.5 meq/g, in particular 0 to 0.4 meq/g, most preferably 0 to 0.2meq/g.

[0096] The above-mentioned “number of milliequivalents of carboxylgroups contained in each gram of polymer (G) (meq/g) as determined onthe unneutralized basis” is intended to include the case where thepolymer (G) is in a salt form, like in the case of polymer (A1), and themethods of calculation for the acid form and salt form are the same asmentioned above for the polymer (A1). The polymer (G) may comprise, asthe carboxyl group-containing constituent unit, any of the constituentunit (II) derived from an unsaturated monocarboxylic acid monomer (b),the constituent unit (V) derived from an unsaturated dicarboxylic cidmonomer (e) and other carboxyl group-containing constituent units, andall carboxyl groups are to be taken into consideration in calculatingthe number of milliequivalents of carboxyl groups. The number ofmilliequivalents of carboxyl groups per gram of the above polymer(meq/g) as determined on the unneutralized basis can be determined notonly by the above-mentioned monomer-based methods of calculation butalso by measuring the acid value of the polymer while taking intoconsideration the kind of counter ion to the carboxyl groups in thepolymer.

[0097] The above polymer (G) can be produced by copolymerizing a monomercomposition comprising, as essential constituents, an unsaturated(poly)alkylene glycol ether monomer (a2), which provides the constituentunit (I′), and an unsaturated monocarboxylic acid ester monomer (c),which provides the constituent unit (III). The method of productionthereof is not limited to such method but may comprise, for example,using a monomer before alkylene oxide addition, namely methallyl alcoholor a like unsaturated alcohol, in lieu of the monomer (a2),copolymerizing the same with a monomer (c) in the presence of apolymerization initiator (where necessary, copolymerizing these monomerswith a further monomer(s) copolymerizable therewith) and, thereafter,causing 1 to 500 moles, on average, of an alkylene oxide to add to theresulting copolymer.

[0098] Referring to the general formulas (1) and (2) given hereinabove,the number of carbon atoms in R¹ in the oxyalkylene group R¹O issuitably 2 to 18 but preferably 2 to 8, more preferably 2 to 4. In thecase of alkylene oxide adducts derived from two or more speciesoptionally selected from among ethylene oxide, propylene oxide, butyleneoxide, styrene oxide and the like, the mode of addition may be of therandom, block and/or alternating type, for instance. For securing abalance between the hydrophilicity and hydrophobicity, it is preferredthat the oxyalkylene group comprises the oxyethylene group as anessential constituent, with the oxyethylene group preferably accountingfor at least 50 mole percent, more preferably at least 90 mole percent.

[0099] In the above general formulas (1) and (2), the mean additionnumbers m and n of moles of oxyalkylene group(s) are appropriately 1 to500. When these mean addition numbers of moles decrease, thehydrophilicity of the polymer obtained tends to decrease, hence thedispersing ability tends to decrease. When they exceed 500, thecopolymerizability tends to decrease. Preferably, they are not less than2, more preferably not less than 5, still more preferably not less than10, in particular not less than 15, most preferably not less than 20.Preferably, they are not more than 300. The preferred range may be, forexample, 2 to 500, 5 to 500, 10 to 500, 15 to 500, or 20 to 300.

[0100] In the above general formula (2), R² may be either a hydrogenatom or a hydrocarbon group containing 1 to 30 carbon atoms. Thehydrocarbon group containing 1 to 30 carbon atoms is preferably ahydrocarbon group not having a radical-polymerizable unsaturated bondand is suitably an alkyl group (aliphatic alkyl group or alicyclic alkylgroup) containing 1 to 30 carbon atoms or a benzene ring-containingaromatic group containing 6 to 30 carbon atoms such as a phenyl group,an alkylphenyl group, a phenylalkyl group, an (alkyl)phenyl-substitutedphenyl group or a naphthyl group. With the increase in the number ofcarbon atoms in the hydrocarbon group, the hydrophobicity increases andthe dispersing ability decreases. Therefore, the number of carbon atomsin R² when this is a hydrocarbon group is preferably 1 to 22, morepreferably 1 to 18, still more preferably 1 to 12, in particular 1 to 4.The case where R² is a hydrogen atom is most preferred.

[0101] In the above general formulas (1) and (2), the number of carbonatoms in the alkenyl group represented by Y is appropriately 2 to 8,preferably not less than 3 but not more than 5. Suitable as the alkenylgroup containing 2 to 8 carbon atoms are vinyl, allyl, methallyl,3-butenyl, 3-methyl-3-butenyl, 3-methyl-2-butenyl, 2-methyl-3-butenyl,2-methyl-2-butenyl and 1,1-dimethyl-2-propenyl. Among them, allyl,methallyl and 3-methyl-3-butenyl are preferred.

[0102] The unsaturated (poly)alkylene glycol ether monomer (a1)represented by the above general formula (1) and the unsaturated(poly)alkylene glycol ether monomer (a2) represented by the abovegeneral formula (2), can be produced by various methods but the typicalmethods are described in the following.

[0103] 1) When the unsaturated (poly)alkylene glycol ether monomer (a1),and R² is a hydrogen atom in the general formula (2), the monomers (a1)and (a2) can be produced by causing 1 to 500 moles of at least onealkylene oxide containing 2 to 18 carbon atoms to add to an unsaturatedalcohol having an alkenyl group containing 3 to 8 carbon atoms such asallyl alcohol, methallyl alcohol, 3-methyl-3-buten-1-ol,3-methyl-2-buten-1-ol or 2-methyl-2-buten-1-ol, in the presence of analkaline catalyst such as potassium hydroxide or sodium hydroxide, oracid catalyst such as boron trifluoride or tin tetrachloride.

[0104] 2) When R² is a hydrocarbon group containing 1 to 30 carbon atomsin the above general formula (2), the monomers can be obtained byreacting a halogenated hydrocarbon containing 1 to 30 carbon atoms suchas methyl chloride with the resulting compound obtained by adding 1 to500 moles of at least one alkylene oxide containing 2 to 18 carbon atomsto an unsaturated alcohol in the above method, in the presence of analkaline catalyst such as sodium hydroxide.

[0105] 3) When R² is a hydrocarbon group containing 1 to 30 carbon atomsin the above general formula (2), the monomers can be obtained byreacting a halogenated alkenyl containing 3 to 8 carbon atoms such asallyl chloride or methallyl chloride with the resulting compoundobtained by adding 1 to 500 moles of at least one alkylene oxidecontaining 2 to 18 carbon atoms to an alcohol or phenol containing 1 to30 carbon atoms such as methanol or phenol, in the presence of analkaline catalyst such as sodium hydroxide, in the different method fromthe method mentioned in the above 2).

[0106] In the production methods 1) and 2), when a compound containingan active hydrogen such as a saturated alcohol other than theabove-mentioned unsaturated alcohol (for example, methanol or ethanol)or water exists in the reaction system on the occasion of adding analkylene oxide to the unsaturated alcohol, a composition which containsa (poly)alkylene glycol not containing a radical-polymerizablesubstituent, namely a non-polymerizable (poly)alkylene glycol (P) notcontaining an alkenyl group as a byproduct, can be obtained by using theabove active hydrogen as a starting material, in addition to the mainproducts unsaturated (poly)alkylene glycol ether monomer (a1) and (a2).On the other hand, in the production method 3), since an unreactedalkylene oxide adducts with a halogenated alkenyl corresponds to anon-polymerizable (poly)alkylene glycol (P) not containing an alkenylgroup, a composition which contains (poly)alkylene glycol (P) as abyproduct can be obtained. A cement admixture comprising a polymerobtained by copolymerization of a monomer composition containing theunsaturated (poly)alkylene glycol ether monomer (a1) or (a2) produced bythe above-mentioned production method 1), 2), or 3), is one preferredmode in the practice of the present invention. Although the(poly)alkylene glycol (P) obtained as a byproduct contains at least oneterminal hydrogen atom, when the (poly)alkylene glycol (P) is a(poly)alkylene glycol containing hydrogen atoms at both terminals, forexample, (poly)ethylene glycol or (poly)ethylene(poly)propylene glycol,the molecular weight of the (poly)alkylene glycol (P) obtained by usingwater containing two active hydrogen as a starting material is higherthan that of unsaturated (poly)alkylene glycol ether monomer (a1) or(a2) obtained by using an unsaturated alcohol containing one activehydrogen as a starting material. In this case, the molecular weight ofthe (poly)alkylene glycol (P) is same or twice level of that ofunsaturated (poly)alkylene glycol ether monomer (a1) or (a2).

[0107] Suited for use as the above unsaturated (poly)alkylene glycolether monomer (a1) are (poly)ethylene glycol allyl ether, (poly)ethyleneglycol methallyl ether, (poly)ethylene glycol 3-methyl-3-butenyl ether,(poly)ethylene(poly)propylene glycol allyl ether,(poly)ethylene(poly)propylene glycol methallyl ether,(poly)ethylene(poly)propylene glycol 3-methyl-3-butenyl ether,(poly)ethylene(poly)butylene glycol allyl ether,(poly)ethylene(poly)butylene glycol methallyl ether and(poly)ethylene(poly)butylene glycol 3-methyl-3-butenyl ether. In thepractice of the present invention, one or more of these can be used asmonomer(s) (a1) for providing the constituent unit (I).

[0108] Suited for use as the above unsaturated (poly)alkylene glycolether monomer (a2) are methoxy(poly)ethylene glycol allyl ether,methoxy(poly)ethylene glycol methallyl ether, methoxy(poly)ethyleneglycol 3-methyl-3-butenyl ether, methoxy(poly)ethylene(poly)propyleneglycol allyl ether, methoxy(poly)ethylene(poly)propylene glycolmethallyl ether, methoxy(poly)ethylene(poly)propylene glycol3-methyl-3-butenyl ether, methoxy(poly)ethylene(poly)butylene glycolallyl ether, methoxy(poly)ethylene(poly)butylene glycol methallyl etherand methoxy(poly)ethylene(poly)butylene glycol 3-methyl-3-butenyl ether,in addition to the compounds mentioned above for the unsaturated(poly)alkylene glycol ether monomer (a1) represented by the generalformula (1). In the practice of the present invention, one or more ofthese can be used as monomer(s) (a2) for providing the constituent unit(I′).

[0109] In the case of the cement admixture (1) comprising the polymer(A1) and polymer (B1) as essential constituents of the invention, two ormore monomers (a1) differing in the mean addition number m of moles ofan oxyalkylene group can be used in combination as the unsaturated(poly)alkylene glycol ether monomer (a1) represented by the generalformula (1). Suitable are combinations of two monomers (a1) differing inm by not less than 10 (preferably differing in m by not less than 20)and combinations of three or more monomers (a1) differing in the meanaddition number m of moles by not less than 10 (preferably differing inm by not less than 20) from one another. As regards the ranges of m's tobe combined, the combination of a monomer (a1) whose mean additionnumber m of moles is 40 to 500 and a monomer (a1) whose m is 1 to 40(with the difference in m being not less than 10, preferably not lessthan 20) and the combination of a monomer (a1) whose mean additionnumber m of moles is 20 to 500 and a monomer (a1) whose m is 10 o 20(with the difference in m being not less than 10, preferably not lessthan 20) are appropriate. It is possible to use a combination of two ormore monomers (a1) differing in the mean addition number m of moles ofan oxyalkylene group(s) in each of the polymers (A1) and (C) or to usethe above monomers differing in the mean addition number m of moles ofan oxyalkylene group(s) from one polymer to another.

[0110] In the case of the cement admixtures (2) to (5) ofthe presentinvention comprising respectively, as essential constituents, the twokinds of polymer, (2) polymer (A2) and polymer (B2), (3) polymer (A3)and polymer (B3), (4) polymer (A3) and polymer (B4), or (5) polymer (G)and polymer (B5), two or more monomers (a2) differing in the meanaddition number n of moles of an oxyalkylene group can be used incombination as the unsaturated (poly)alkylene glycol ether monomer (a2)represented by the general formula (2). Suitable are combinations of twomonomers (a2) differing in n by not less than 10 (preferably differingin n by not less than 20) and combinations of three or more monomers(a2) differing in the mean addition number n of by not less than 10(preferably differing in n by not less than 20) from one another. Asregards the ranges of n's to be combined, the same ranges as mentionedabove for m in the case of the cement admixture (1) are appropriate. Itis possible to use a combination of two or more monomers (a2) differingin the mean addition number n of moles of an oxyalkylene group(s) ineach of the polymers (A2), (A3) and (G) or to use the above monomersdiffering in the mean addition number n of moles of an oxyalkylenegroup(s) from one polymer to another.

[0111] Preferred as the unsaturated monocarboxylic acid monomer (b),which provides the constituent unit (II), are (meth)acrylic acidmonomers. Thus preferred are acrylic acid, methacrylic acid and crotonicacid, and monovalent metal salts, divalent metal salts, ammonium saltsand organic amine salts of these. From the copolymerizability viewpoint,however, (meth)acrylic acid and salts thereof are more preferred. Two ormore of these monomers (b) may be used in combination. In the polymers(A1), (C), (A2), (A3), and (G), however, it is preferred that themonomer (b) used to provide the constituent unit (II) comprise acrylicacid or a salt thereof as an essential constituent.

[0112] The unsaturated monocarboxylic acid ester monomer (c) used toprovide the constituent unit (III) is an esterification product derivedfrom an unsaturated monocarboxylic acid and a monohydric alcohol,preferably an esterification product derived from a (meth)acrylic acidmonomer, namely acrylic acid, methacrylic acid or crotonic acid, used asthe unsaturated monocarboxylic acid, and a monohydric alcohol. Morespecifically, the (poly)alkylene glycol mono(meth)acrylic acid estermonomer (d) capable of providing the constituent unit (IV) representedby the above general formula (3) or a hydrophobic unsaturatedmonocarboxylic acid ester monomer (f) capable of providing theconstituent unit (VI) represented by the general formula (4) ispreferred as the unsaturated monocarboxylic acid ester monomer (c). Themonomer (c) providing the constituent unit (III) may comprise one singlespecies or two or more of such species as mentioned above.

[0113] In the polymer (G), in particular, the constituent unit (III)derived from an unsaturated monocarboxylic acid ester monomer (c)preferably comprises an acrylic acid ester monomer-derived constituentunit as an essential constituent unit. Thus, the unsaturatedmonocarboxylic acid ester monomer (c), which provides the constituentunit (III), preferably comprises, as an essential constituent, anesterification product derived from acrylic acid and a monohydricalcohol. More specifically, it is preferred that the constituent unit(IV) represented by the above general formula (3) comprise, as anessential constituent unit, a (poly)alkylene glycol monoacrylic acidester monomer-derived constituent unit (corresponding to the case where,in the above general formula (3), R³ and R⁴ each is a hydrogen atom) orthe constituent unit (VI) represented by the above general formula (4)comprise a hydrophobic acrylic acid ester monomer-derived constituentunit (corresponding to the case where, in the above general formula (4),R⁷ and R⁸ each is a hydrogen atom) as an essential constituent unit.

[0114] When the (poly)alkylene glycol mono(meth)acrylic acid estermonomer (d), which provides the constituent unit (IV) represented by theabove general formula (3), is used as the unsaturated monocarboxylicacid ester monomer (c), which provides the constituent unit (III), thenumber of carbon atoms contained in the oxyalkylene group R⁵O in theabove general formula (3) is appropriately 2 to 18 but preferably 2 to8, more preferably 2 to 4. In the case of adducts of two or morealkylene oxides arbitrarily selected from among ethylene oxide,propylene oxide, butylene oxide, styrene oxide and the like, the mode ofaddition may be any of the random, block, alternating or other additiontypes. In the above general formula (3), the mean addition number n ofmoles of an oxyalkylene group(s) is appropriately 1 to 500 but ispreferably 1 to 300, more preferably 1 to 200, still more preferably 1to 100, in particular 1 to 50. As this mean addition number of molesincreases, the copolymerizability with the unsaturated (poly)alkyleneglycol ether monomer (a1) which provides the constituent unit (I) or theunsaturated (poly)alkylene glycol ether monomer (a2) which provides theconstituent unit (I′), tends to decrease. Furthermore, in the abovegeneral formula (3), R⁶ may be a hydrogen atom or a hydrocarbon groupcontaining 1 to 30 carbon atoms. Appropriate as the hydrocarbon groupcontaining 1 to 30 carbon atoms are those specifically mentionedhereinabove referring to R². Since, however, the hydrophobicityincreases and the dispersing ability decreases as the increase in thenumber of carbon atoms in the hydrocarbon group, the number of carbonatoms in the hydrocarbon group represented by R⁶ is preferably 1 to 22,more preferably 1 to 18, still more preferably 1 to 12, in particular 1to 5.

[0115] When the (poly)alkylene glycol mono(meth)acrylic acid estermonomer (d), which provides the constituent unit (IV) represented by theabove general formula (3), is used as the unsaturated monocarboxylicacid ester monomer (c) to provide the constituent unit (III), thefollowing are suited for use as the monomer (d): hydroxyalkyl(meth)acrylates (corresponding to the case where, in the above generalformula (3), p is 1 and R⁶ is a hydrogen atom) such as hydroxyethyl(meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl(meth)acrylate; various polyalkylene glycol mono(meth)acrylates(corresponding to the case where, in the above general formula (3), p isnot less than 2 and R⁶ is a hydrogen atom) such as polyethylene glycolmono(meth)acrylate, polypropylene glycol mono(meth)acrylate andpolybutylene glycol mono(meth)acrylate; various alkoxy(poly)alkyleneglycol mono(meth)acrylates such as methoxy(poly)ethylene glycolmono(meth)acrylate and methoxy(poly)ethylene(poly)propylene glycolmono(meth)acrylate; and the like.

[0116] When the (poly)alkylene glycol mono(meth)acrylic acid estermonomer (d) is used, the polymer (G), in particular, preferablycomprises a (poly)alkylene glycol monoacrylic acid ester monomer-derivedconstituent unit as an essential constituent unit. Suitable as themonomer which provides such constituent unit are hydroxyalkyl acrylates(corresponding to the case where, in the above general formula (3), p is1 and R³, R⁴ and R⁶ each is a hydrogen atom) such as 2-hydroxyethylacrylate, 2-hydroxypropyl acrylate and 2-hydroxybutyl acrylate; variouspolyalkylene glycol monoacrylates (corresponding to the case where, inthe above general formula (3), p is not less than 2 and R³, R⁴ and R⁶each is a hydrogen atom) such as polyethylene glycol monoacrylate,polypropylene glycol monoacrylate and polybutylene glycol monoacrylate;and various alkoxy(poly)alkylene glycol monoacrylates (corresponding tothe case where, in the above general formula (3), R³ and R⁴ each is ahydrogen atom and R⁶ is a hydrocarbon group containing 1 to 30 carbonatoms) such as methoxy(poly)ethylene glycol monoacrylate andmethoxy(poly)ethylene(poly)propylene glycol monoacrylate.

[0117] When the hydrophobic unsaturated monocarboxylic acid estermonomer (f), which provides the constituent unit (VI) represented by theabove general formula (4), is used as the unsaturated monocarboxylicacid ester monomer (c) to provide the constituent unit (III), R⁹ in thegeneral formula (4) may be a hydrocarbon group containing 1 to 30 carbonatoms. Suitable as the hydrocarbon group containing 1 to 30 carbon atomsare those specifically mentioned above referring to R². Since, however,the hydrophobicity increases and the dispersing ability decreases as theincrease in the number of carbon atoms in the hydrocarbon group, thenumber of carbon atoms in the hydrocarbon group represented by R⁹ ispreferably 1 to 22, more preferably 1 to 18, still more preferably 1 to12, most preferably 1 to 4.

[0118] When the hydrophobic unsaturated monocarboxylic acid estermonomer (f), which provides the constituent unit (VI) represented by theabove general formula (4), is used as the unsaturated monocarboxylicacid ester monomer (c) to provide the constituent unit (III)), thefollowings are suited for use as the monomer (f): alkyl (meth)acrylatessuch as methyl (meth)acrylate, ethyl (meth)acrylate, propyl(meth)acrylate, butyl (meth)acrylate, octyl (meth)acrylate andcyclohexyl (meth)acrylate; and aromatic (meth)acrylates such as phenoxy(meth)acrylate and benzyl (meth)acrylate.

[0119] Referring to the polymer (G), in particular, when the hydrophobicunsaturated monocarboxylic acid ester monomer (f) is used, it ispreferred that a constituent unit derived from a hydrophobic acrylicacid ester monomer as an essential constituent unit is comprised.Referring to a monomer, which provides the above constituent unit, alkylacrylates corresponding to the case where R⁷ and R⁸ in the generalformula (4) are hydrogen atoms and R⁹ is an alkyl group containing 1 to30 carbon atoms, more preferably 1 to 22 carbon atoms, still morepreferably 1 to 18 carbon atoms, in particular 1 to 12 carbon atoms,most preferably 1 to 4 carbon atoms, are preferred. Suited for use asthe above alkyl acrylates are methyl acrylate, ethyl acrylate, propylacrylate and butyl acrylate.

[0120] In producing the above polymers (A1), (C), (A2), (A3), and (G),an unsaturated dicarboxylic acid monomer (e) which provides theconstituent unit (V) and/or a monomer (g) which provides the constituentunit (VII) can be used in addition to the monomers providing theessential constituent units.

[0121] Suitable as the unsaturated dicarboxylic acid monomer (e), whichprovides the constituent unit (V) are maleic acid, citraconic acid,fumaric acid, and metal salts, ammonium salts and amine salts of theseand, further, maleic anhydride and citraconic anhydride as theanhydrides thereof. Among them, maleic acid or a salt thereof and maleicanhydride are preferred. These monomers (e) may be used singly or two ormore may be used in combination.

[0122] The monomer (g), which provides the above-mentioned constituentunit (VII), is a monomer other than the monomers (a1) to (f) butcopolymerizable with the other monomers. Suitable as such monomer (g)are half esters and diesters derived from unsaturated dicarboxylic acidmonomers, such as maleic acid, maleic anhydride, fumaric acid, itaconicacid and citraconic acid, and alcohols containing 1 to 30 carbon atoms;half amides and diamides derived from the above-mentioned unsaturateddicarboxylic acid monomers and amines containing 1 to 30 carbon atoms;half esters and diesters derived from the above-mentioned unsaturateddicarboxylic acid monomers and alkyl(poly)alkylene glycols, which areadducts of 1 to 500 moles of an alkylene oxide(s) containing 2 to 18carbon atoms with the above-mentioned alcohols or amines; half estersand diesters derived from the above-mentioned unsaturated dicarboxylicacid monomers and glycols containing 2 to 18 carbon atoms orpolyalkylene glycols, which are adducts of 2 to 500 moles of an alkyleneoxide(s) with such glycols; half amides derived from maleamidic acid andglycols containing 2 to 18 carbon atoms or polyalkylene glycols, whichare adducts of 2 to 500 moles of an alkylene oxide(s) with such glycols;(poly)alkylene glycol di(meth)acrylates such as triethylene glycoldi(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, polypropyleneglycol di(meth)acrylate and (poly)ethylene glycol-(poly)propylene glycoldi(meth)acrylate; multifunctional (meth)acrylates such as hexanedioldi(meth)acrylate, trimethylolpropane tri(meth)acrylate andtrimethylolpropane di(meth)acrylate; (poly)alkylene glycol dimaleatessuch as triethylene glycol dimaleate and polyethylene glycol dimaleate;unsaturated sulfonic acids and monovalent metal salts, divalent metalsalts, ammonium salts and organic amine salts thereof, for examplevinylsulfonates, (meth)allylsulfonates, 2-(meth)acryloxyethylsulfonates,3-(meth)acryloxypropylsulfonates,3-(meth)acryloxy-2-hydroxypropylsulfonates,3-(meth)acryloxy-2-hydroxypropyl sulfophenyl ether,3-(meth)acryloxy-2-hydroxypropyloxysulfobenzoates,4-(meth)acryloxybutylsufonates, (meth)acrylamidomethylsulfonates,(meth)acrylamidoethylsulfonates, 2-methylpropanesulfonic acid(meth)acrylamide, and styrenesulfonic acid; amides derived fromunsaturated monocarboxylic acids and amines containing 1 to 30 carbonatoms, for example methyl(meth)acrylamide; vinyl aromatics such asstyrene, α-methylstyrene, vinyltoluene and p-methylstyrene; alkanediolmono(meth)acrylates such as 1,4-butanediolmono(meth)acrylate,1,5-pentanediol mono(meth)acrylate and 1,6-hexanediolmono(meth)acrylate; dienes such as butadiene, isoprene,2-methyl-1,3-butadiene and 2-chloro-1,3-butadiene; unsaturated amidessuch as (meth)acrylamide, (meth)acrylalkylamides,N-methylol(meth)acrylamide and N,N-dimethyl(meth)acrylamide; unsaturatedcyano compounds such as (meth)acrylonitrile and α-chloroacrylonitrile;unsaturated esters such as vinyl acetate and vinyl propionate;unsaturated amines such as aminoethyl (meth)acrylate, methylaminoethyl(meth)acrylate, dimethylaminoethyl (meth)acrylate, dimethylaminopropyl(meth)acrylate, dibutylaminoethyl (meth)acrylate and vinylpyridine;divinyl aromatics such as divinylbenzene; cyanurates such as triallylcyanurate; and siloxane derivatives such aspolydimethylsiloxanepropylaminomaleamidic acid,polydimethylsiloxaneaminopropyleneaminomaleamidic acid,polydimethylsiloxane-bis(propylaminomaleamidic acid),polydimethylsiloxane-bis(dipropyleneaminomaleamidic acid),polydimethylsiloxane-(1-propyl-3-acrylate),polydimethylsiloxane-(1-propyl-3-methacrylate),polydimethylsiloxane-bis(1-propyl-3-acrylate) andpolydimethylsiloxane-bis (1-propyl-3-methacrylate). These may be usedsingly or two or more of them may be used combinedly.

[0123] The above polymers (B1), (B2), (B3), (B4) and (B5) areoxyalkylene group- or polyoxyalkylene group- and carboxylgroup-containing polymers. These may be used singly or two or more ofthem may be used combinedly. Further, in this description, polymer (B)means all of the polymer (B1), (B2), (B3), (B4) and (B5).

[0124] The above polymer (B) is a polymer other than the correspondingpolymer (A) and polymer (G) in the cement admixture. Namely, the polymer(B1) is a polymer other than the polymer (A1) in the cement admixture(1), the polymer (B2) is a polymer other than the polymer (A2) in thecement admixture (2), the polymer (B3) is a polymer other than thepolymer (A3) in the cement admixture (3), the polymer (B4) is a polymerother than the polymer (A3) in the cement admixture (4), and the polymer(B5) is a polymer other than the polymer (G) in the cement admixture(5).

[0125] Suitable as the oxyalkylene or polyoxyalkylene group, which is anessential structural element of the polymer (B), are oxyalkylene groupscontaining 2 to 18 carbon atoms, or polyoxyalkylene groups, which areadducts of one or more of such oxyalkylene groups with a mean additionnumber of moles thereof exceeding 1, preferably not less than 2, morepreferably not less than 5, still more preferably not less than 10.Referring to the above (poly)oxyalkylene groups, the number of carbonatoms in the oxyalkylene group is suitably 2 to 18, preferably 2 to 8,more preferably 2 to 4. As for the alkylene oxide adducts derived fromtwo or more alkylene oxides arbitrarily selected from among ethyleneoxide, propylene oxide, butylene oxide and styrene oxide, among others,the mode of addition may be of any type, random, block or alternating,for instance. Preferably, however, the oxyalkylene groups comprise anoxyethylene group(s) as essential constituent(s) and, more preferably,oxyethylene groups account for not less than 50 mole percent thereof.

[0126] Suitable as the polymers (B1), (B2) and (B5) in the above polymer(B) are polymers (A) (polymers (A1), (A2) and (A3) such as theabove-mentioned polymer (C)) or (G) other than the polymer (A) or (G) tobe combined, a polymer (polymer (B3)) comprising, as essentialconstituent units, the constituent unit (IV) derived from (poly)alkyleneglycol mono(meth)acrylic acid ester monomer (d) represented by the abovegeneral formula (3) and the constituent unit (II)derived from anunsaturated monocarboxylic acid monomer (b), a polymer (polymer (B4))comprising, as essential constituent units, the constituent unit (I′)derived from an unsaturated (poly)alkylene glycol ether monomer (a2)represented by the above general formula (2) and the constituent unit(V) derived from an unsaturated dicarboxylic acid monomer (e), andhydrophilic graft polymers derived from polyether compounds andunsaturated carboxylic acid monomers by graft polymerization, asdescribed in Japanese Kokai Publication Hei-07-53645, Japanese KokaiPublication Hei-08-208769 and Japanese Kokai Publication H0ei-8-208770.Among them, the polymer (B3) or (B4) is preferably used. Thus, inpreferred embodiments, the polymer (B) is one of the above-mentionedpolymers (B3) and (B4). The polymers (B3) and polymers (B4) may be usedsingly or two or more of them may be used in combination.

[0127] The cement admixtures (1) to (4) according to the presentinvention comprise at least one polymer (A) and at least one polymer(B), respectively. The combination of polymer (A) and polymer (B)includes the case (1) in which the polymer (A) is combined with thepolymer (B) which is other than the polymer (A) and/or the case (2) inwhich the polymer (A) is combined with the polymer (B) which is anotherpolymer (A) (polymer (A′) ). In case (1), such cement admixturecomprises, as polymer (B), a polymer other than the polymer (A), namelysuch a polymer (B3) or polymer (B4) as mentioned above and, in case (2),it comprises two or more polymers (A), at least one of which serves aspolymer (A) and in which at least one polymer (polymer (A′)) other thanthe polymer (A) serves as polymer (B). The two or more polymers in case(2) are preferably two or more polymers (A) differing in acid value,molecular weight, constituent unit structure and/or constituent unitcomposition, for instance. In the cement admixture (1), suitable as thecombination of two or more polymers differing in constituent unitstructure is the combination of polymers differing in the mean additionnumber m of moles of an oxyalkylene group(s) of the unsaturated(poly)alkylene glycol ether monomer (a1) represented by the generalformula (1). In the cement admixtures (2), (3), and (4), suitable as thecombination of two or more polymers differing in constituent unitstructure is the combination of polymers differing in the mean additionnumber n of moles of an oxyalkylene group(s) of the unsaturated(poly)alkylene glycol ether monomer (a2) represented by the generalformula (2).

[0128] In another preferred specific combination of polymer (A1) andpolymer (B1) in the cement admixture (1) according to the presentinvention, the above-mentioned polymer (C) is used as polymer (A1) and apolymer (A) (polymer (A1), (A2) or (A3)), other than the polymer (C), isused as polymer (B1). Further preferred combinations are as follows:combination of polymer (A1) and, as polymer (B1), a polymer (A) (polymer(A1), (A2) or (A3)) differing in constituent unit(s) from the polymer(A1); combination of polymer (A1) and, as polymer (B1), a polymer (A)identical in constituent units to but differing in constituent unitcontent ratio from the polymer (A1); combination of the above-mentionedpolymer(C) as polymer (A1) and, as polymer (B1), a polymer (A) (polymer(A1), (A2) or (A3)) differing in constituent unit(s) from the polymer(C); combination of the above-mentioned polymer (C) as polymer (A1) and,as polymer (B1), a polymer (A1) identical in constituent units to butdiffering in constituent unit content ratio from the polymer (C); and soforth. Preferred among others, however, is the combined use of two ormore polymers differing in the mean addition number m of moles of theoxyalkylene group(s) in the unsaturated (poly)alkylene glycol ethermonomer (a1) presented by the above general formula (1), which providesan essential constituent unit in the polymer (A1) or (C).

[0129] In another preferred specific combination of polymer (A2) and(B2) in the cement admixture (2) according to the present invention, theabove-mentioned polymer (C) is used as polymer (A2) and a polymer (A)(polymer (A1), (A2) or (A3)), other than the polymer (C), is used aspolymer (B2). Further preferred combinations are as follows: combinationof polymer (A2) and, as polymer (B2), a polymer (A) (polymer (A1), (A2)or (A3)) differing in constituent unit(s) from the polymer (A2);combination of polymer (A2) and, as polymer (B2), a polymer (A)identical in constituent units to but differing in constituent unitcontent ratio from the polymer (A2); combination of the above-mentionedpolymer(C) as polymer (A2) and, as polymer (B2), a polymer (A) (polymer(A1), (A2) or (A3)) differing in constituent unit(s) from the polymer(C); combination of the above-mentioned polymer (C) as polymer (A2) and,as polymer (B2), a polymer (A2) identical in constituent units to butdiffering in constituent unit content ratio from the polymer (C); and soforth. Preferred among others, however, is the combined use of two ormore polymers differing in the addition number n of moles of theoxyalkylene group(s) in the unsaturated (poly)alkylene glycol ethermonomer (a2) presented by the above general formula (2), which providesan essential constituent unit in the polymer (A2) or polymer (C).

[0130] In the cement admixture (5) according to the present invention,preferred combinations of the polymer (G) and (B5) are as follows:combination of the polymer (G) and, as polymer (B5), a polymer (G)differing in constituent unit(s) from the polymer (G); combination ofpolymer (G) and, as polymer (B5), a polymer (G) identical in constituentunits to but differing in constituent unit content ratio from thepolymer (G); combination of polymer (G) and, as polymer (B5), a polymer(A) (a polymer (A1), (A2) or (A3)) other than the polymer (G)

[0131] The above polymer (B3) is a polymer comprising, as essentialconstituent units, the constituent unit (IV) derived from (poly)alkyleneglycol mono(meth)acrylic acid ester monomer (d) represented by the abovegeneral formula (3) and the constituent unit (II) derived from anunsaturated monocarboxylic acid monomer (b). It may further compriseanother or other copolymerizable monomer-derived constituent unit orunits. Each of these constituent units in the polymer (B3) may compriseone single species or two or more species.

[0132] The ratio between the constituent unit (IV) and constituent unit(II) (constituent unit (IV)/constituent unit (II); % by mass) in theabove polymer (B3) is preferably 1 to 99/99 to 1. The total content (%by mass) of the constituent unit (IV) and constituent unit (II) in thepolymer (B3) is preferably 50 to 100% by mass, more preferably 70 to100% by mass, based on the whole polymer (B3). The upper limit to thecontent of the constituent unit (II) can be placed at a level such thatthe number of milliequivalents of carboxyl groups contained in thepolymer (B3) as determined on the unneutralized basis falls within therange to be mentioned later herein.

[0133] Further, for attaining a high level of dispersing ability, thenumber of milliequivalents of carboxyl groups contained in each gram ofpolymer (B3) as determined on the unneutralized basis is preferably 0.3to 3.5 meq/g, and the proportions of the constituent units constitutingthe polymer (B3) are preferably selected so that the number ofmilliequivalents of carboxyl groups in the polymer (B3) may fall withinsuch range. The number of milliequivalents of carboxyl groups is morepreferably 0.3 to 3.0 meq/g, still more preferably 0.4 to 2.5 meq/g. Thepolymer (B3) may contain, in addition to the carboxyl group-containingconstituent unit (II) derived from an unsaturated monocarboxylic acidmonomer (b), a further carboxyl group-containing constituent unit suchas the above-mentioned constituent unit (V) derived from an unsaturateddicarboxylic acid monomer (e), hence the number of milliequivalents ofcarboxyl groups contained in the polymer (B3) is not always limited tothat owing to the constituent unit (II).

[0134] The above-mentioned “number of milliequivalents of carboxylgroups contained in each gram of polymer (B3) (meq/g) as determined onthe unneutralized basis” is intended to include the case where thepolymer (B3) is in a salt form, and the methods of calculation for theacid form and salt form are the same as mentioned above for the polymer(A1). When the polymer (B3) comprises a further carboxyl-containingconstituent unit (e.g. the constituent unit (V) derived from anunsaturated dicarboxylic acid monomer (e)) other than the constituentunit (II), the number of milliequivalents of carboxyl groups asresulting from such further unit should be included in the calculation.The number of milliequivalents of carboxyl groups per gram of thepolymer (B3) (meq/g) as determined on the unneutralized basis can bedetermined not only by the above-mentioned monomer-based methods ofcalculation but also by measuring the acid value of the polymer whiletaking into consideration the kind of counter ion to the carboxyl groupsin the polymer.

[0135] The above polymer (B3) can be produced, for example, bycopolymerizing a monomer component comprising, as essentialconstituents, a (poly)alkylene glycol mono(meth)acrylic acid estermonomer (d), which provides the constituent unit (IV), and anunsaturated monocarboxylic acid monomer (b), which provides theconstituent unit (II). The method of production thereof is not limitedto such method but may comprise, for example, directly esterifying atleast part of the carboxyl groups of a polymer obtained by polymerizinga monomer component containing a (meth)acrylic acid monomer, namelyacrylic acid, methacrylic acid or crotonic acid, as an essentialconstituent, with an alkoxypolyalkylene glycol having a hydrocarbongroup containing 1 to 30 carbon atoms at one terminal.

[0136] When, in producing the above polymer (B3), a (poly)alkyleneglycol mono(meth)acrylic acid ester monomer (d), which provides theconstituent unit (IV), represented by the above general formula (3) isused, the number of carbon atoms in the oxyalkylene group R⁵O issuitably 2 to 18 but preferably 2 to 8, more preferably 2 to 4, in theabove general formula (3). In the case of alkylene oxide adducts derivedfrom two or more species optionally selected from among ethylene oxide,propylene oxide, butylene oxide, styrene oxide and the like, the mode ofaddition may be of the random, block and/or alternating type, forinstance. For securing a balance between the hydrophilicity andhydrophobicity, it is preferred that the oxyalkylene group comprises theoxyethylene group as an essential constituent, with the oxyethylenegroup preferably accounting for at least 50 mole percent, morepreferably at least 90 mole percent. In the above general formula (3),the mean addition number n of moles of oxyalkylene group(s) isappropriately 1 to 500 but preferably is 2 to 500, more preferably 5 to500, still more preferably 10 to 500, in particular 15 to 500, mostpreferably 20 to 300. When this mean addition number of moles decreases,the hydrophilicity of the polymer obtained tends to decrease, hence thedispersing ability tends to decrease. When it exceeds 500, thecopolymerizability tends to decrease. Further, in the above generalformula (3), R⁶ may be either a hydrogen atom or a hydrocarbon groupcontaining 1 to 30 carbon atoms but preferably is a hydrocarbon groupcontaining 1 to 30 carbon atoms. Suitable as the hydrocarbon groupcontaining 1 to 30 carbon atoms are those specifically mentionedhereinabove referring to R². With the increase in the number of carbonatoms in the hydrocarbon group, the hydrophobicity increases and thedispersing ability decreases. Therefore, the number of carbon atoms inR⁶ when this is a hydrocarbon group is preferably 1 to 22, morepreferably 1 to 18, still more preferably 1 to 12, in particular 1 to 5.

[0137] When a (poly)alkylene glycol mono(meth)acrylic acid ester monomer(d), which provides the constituent unit (IV) represented by the abovegeneral formula (3), is used in producing the above polymer (B3), themonomer (d) includes, among others, (meth)acrylic acid- or crotonicacid-C₂₋₁₈ alkylene oxide adducts; esterification products derived from(meth)acrylic acid or crotonic acid on one hand and, on the other,alkoxypolyalkylene glycols obtained by addition of an alkylene oxide(s)containing 2 to 18 carbons atoms to any of saturated aliphatic alcoholscontaining 1 to 30 carbon atoms, such as methanol, ethanol, 2-propanol,1-butanol, 1-pentanol, 1-hexanol, octanol, 2-ethyl-1-hexanol, nonylalcohol, lauryl alcohol, cetyl alcohol and stearyl alcohol, unsaturatedaliphatic alcohols containing 3 to 30 carbon atoms, such as crotylalcohol and oleyl alcohol, alicyclic alcohols containing 3 to 30 carbonatoms, such as cyclohexanol, and aromatic alcohols containing 6 to 30carbon atoms, such as phenol, phenylmethanol (benzyl alcohol),methylphenol (cresol), dimethylphenol (xylenol) and nonylphenol. Asspecific examples of the monomer (d), there may be mentioned the samemonomers as mentioned above referring to the case where the monomer (d),which provides the constituent unit (IV), represented by the abovegeneral formula (3) is used as the unsaturated monocarboxylic acid estermonomer (c) to provide the constituent unit (III) in the polymer (C).The monomer (d), which provides the constituent unit (IV), to be used inproducing the polymer (B3) may comprise one single species or acombination of two or more species.

[0138] The unsaturated monocarboxylic acid monomer (b), which providesthe constituent unit (II), to be used in producing the polymer (B3) ispreferably a (meth)acrylic acid monomer. Preferred species are acrylicacid, methacrylic acid, crotonic acid, and monovalent metal salt,divalent metal salts, ammonium salts, and organic amine salts thereof.From the copolymerizability viewpoint, however, (meth)acrylic acid andsalts thereof are more preferred. The monomer (b) may comprise onesingle species or a combination of two or more species.

[0139] In addition to the monomer constituents providing the essentialconstituent units, any of an unsaturated dicarboxylic acid monomer (e),which provides the constituent unit (V), a hydrophobic unsaturatedmonocarboxylic acid ester monomer (f), which provides the constituentunit (VI), and a monomer (g), which provides the constituent unit (VII),may be used as another copolymerizable monomer in producing the polymer(B3). Preferred species of such monomers are those already mentionedhereinabove.

[0140] The above-mentioned polymer (B4) is a polymer comprising, asessential constituent units, the constituent unit (I′) derived from anunsaturated (poly)alkylene glycol ether monomer (a2) represented by theabove general formula (2) and the constituent unit (V) derived from anunsaturated dicarboxylic acid monomer (e). It may further compriseanother or other copolymerizable monomer-derived constituent unit orunits. These constituent units in the polymer (B4) each may comprise onesingle species or two or more species.

[0141] In the above polymer (B4), the constituent unit (I′) andconstituent unit (V) each accounts for at least 1% by mass of allconstituent units, and the proportion of the constituent unit (I′) ispreferably not more than 50 mole percent of all constituent units. Whenthe proportion of the constituent unit (I′) is less than 1% by mass, thecontent, in the polymer (B4), of the unsaturated (poly)alkylene glycolether monomer (a2)-derived oxyalkylene group(s) is too low. When theproportion of the constituent unit (V) is less than 1% by mass, thecontent, in the polymer (B4), of the unsaturated dicarboxylic acidmonomer (e)-derived carboxyl groups is too low. In either case, thedispersing ability tends to decrease. Further, since the unsaturated(poly)alkylene glycol ether monomer (a2) is low in polymerizability, itis preferred that the proportion of the constituent unit (I′) be notmore than 50 mole percent of all constituent units so that the polymer(B4) can be obtained with high dispersing ability and in high yields.The total content (% by mass), in the polymer (B4), of the constituentunits (I′) and (V) is preferably 50 to 100% by mass, more preferably 70to 100% by mass, on the whole polymer (B4) basis.

[0142] Further, for attaining a high level of dispersing ability, thenumber of milliequivalents of carboxyl groups contained in each gram ofthe polymer (B4) as determined on the unneutralized basis is preferably0.3 to 3.5 meq/g, and the proportions of the constituent unitsconstituting the polymer (B4) are preferably selected so that the numberof milliequivalents of carboxyl groups in the polymer (B4) may fallwithin such range. The number of milliequivalents of carboxyl groups ismore preferably 0.3 to 3.0 meq/g, still more preferably 0.4 to 2.5meq/g. The upper limit to the content of the constituent unit (V) can beplaced at a level such that the number of milliequivalents of carboxylgroups contained in the polymer (B4) as determined on the unneutralizedbasis is within the above range.

[0143] The above-mentioned “number of milliequivalents of carboxylgroups contained in each gram of polymer (B4) (meq/g) as determined onthe unneutralized basis” is intended to include the case where thepolymer (B4) is in a salt form, and the methods of calculation for theacid form and salt form are the same as mentioned above for the polymer(A1). The polymer (B4) may contain, in addition to the constituent unit(V) derived from an unsaturated dicarboxylic acid monomer (e), a furthercarboxyl-containing constituent unit such as the above-mentionedconstituent unit (II) derived from an unsaturated monocarboxylic acidmonomer (b), hence the number of milliequivalents of carboxyl groupscontained in the polymer (B4) is not always limited to that owing to theconstituent unit (V). The number of milliequivalents of carboxyl groupsper gram of the polymer (B4) (meq/g) as determined on the unneutralizedbasis can be determined not only by the above-mentioned monomer-basedmethods of calculation but also by measuring the acid value of thepolymer while taking into consideration the kind of counter ion to thecarboxyl groups in the polymer.

[0144] The above polymer (B4) can be produced, for example, bycopolymerizing a monomer component comprising, as essentialconstituents, an unsaturated (poly)alkylene glycol ether monomer (a2),which provides the constituent unit (I′), and an unsaturateddicarboxylic acid monomer (e), which provides the constituent unit (V).The method of production thereof is not limited to such method but maycomprise, for example, using a monomer before alkylene oxide addition,namely methallyl alcohol or a like unsaturated alcohol, in lieu of themonomer (a2), copolymerizing the same with a monomer (e) in the presenceof a polymerization initiator (where necessary copolymerizing thesemonomers with a further monomer(s) copolymerizable therewith) and,thereafter, causing 1 to 500 moles, on average, of an alkylene oxide toadd to the resulting copolymer.

[0145] As for the details and specific examples of the polymer(B4)-constituting constituent units and the monomers which provide theconstituent units, the corresponding descriptions given hereinabovereferring to the polymer (A1) or (A2) are to be referred to.

[0146] The above polymers (A), (B) and (G), can be produced bypolymerizing monomer compositions comprising the monomers mentionedabove, using a polymerization initiator. The polymerization can becarried out in the manner of solution polymerization or bulkpolymerization, for instance.

[0147] The solution polymerization can be carried out either batchwiseor continuously. Suited for use as the solvent on that occasion arewater; lower alcohols such as methyl alcohol, ethyl alcohol andisopropyl alcohol; aromatic or aliphatic hydrocarbons such as benzene,toluene, xylene, cyclohexane and n-hexane; ester compounds such as ethylacetate; and ketone compounds such as acetone and methyl ethyl ketone.These may be used singly or two or more of them may be used incombination. In view of the solubilities of the starting monomers andthe polymers (A), (B) and (G) and the convenience in using the polymers,at least one solvent selected from the group consisting of water andlower alcohols containing 1 to 4 carbon atoms is preferably used. Inthat case, methyl alcohol, ethyl alcohol and isopropyl alcohol areparticularly effective among lower alcohols containing 1 to 4 carbonatoms.

[0148] In carrying out the polymerization in aqueous solution, use ismade, as a radical polymerization initiator, a water-solublepolymerization initiator, for example, a persulfate salt such asammonium persulfate, sodium persulfate or potassium persulfate; hydrogenperoxide; or a water-soluble azo initiator, for example an azoamidinecompound such as 2,2′-azobis-2-methylpropionamidine hydrochloride, acyclic azoamidine compound such as2,2′-azobis-2-(2-imidazolin-2-yl)propane hydrochloride, or an azonitrilecompound such as 2-carbamoylazoisobutyronitrile and, on that occasion,an accelerator may be used combinedly, for example an alkali metalsulfite such as sodium hydrogen sulfite, a metabisulfite, sodiumhypophosphate, an Fe(II) salt such as Mohr's salt, sodiumhydroxymethanesulfinate dihydrate, hydroxylamine hydrochloride,thiourea, L-ascorbic acid (salt) or erythorbic acid (salt). Whenhydrogen peroxide is used as the water-soluble polymerization initiator,such an accelerator as L-ascorbic acid (salt) is preferably used incombination.

[0149] In carrying out the polymerization using a lower alcohol,aromatic hydrocarbon, aliphatic hydrocarbon, ester compound or ketonecompound as the solvent, a peroxide such as benzoyl peroxide or lauroylperoxide; a hydroperoxide such as cumene hydroperoxide; or such an azocompound as azobisisobutyronitrile, for instance, is used as thepolymerization initiator. On that occasion, an accelerator such as anamine compound may be used in combination. Further, when a mixed solventcomposed of water and a lower alcohol is used, an appropriatepolymerization initiators or polymerization initiator-acceleratorcombination can be selected from among the above-mentioned variousinitiators or initiator-accelerator combinations. The polymerizationtemperature may appropriately be selected depending on the solvent andpolymerization initiator employed. Generally, the polymerization iscarried out at 0 to 120° C.

[0150] The above-mentioned bulk polymerization is carried out at atemperature of 50 to 200° C. using, as the polymerization initiator,peroxide such as benzoyl peroxide or lauroyl peroxide; a hydroperoxidesuch as cumene hydroperoxide; or an azo compound such asazobisisobutyronitrile, for instance.

[0151] An injection method of each monomer to a reaction vessel is notparticularly restricted but includes a method comprising injecting thewhole monomers to a reaction vessel collectively at the initial stage, amethod comprising injecting the whole monomers to a reaction vesseldivisionally or continuously, and a method comprising injecting part ofmonomers to a reaction vessel at the initial stage and then injectingthe remnant to a reaction vessel divisionally or continuously.Specifically, there may be mentioned the following methods (1) to (4).

[0152] (1) A method comprising injecting the whole monomers to areaction vessel continuously.

[0153] (2) A method comprising injecting the whole monomer (a1) or (a2)to a reaction vessel collectively at the initial stage, and theninjecting the other monomers to a reaction vessel continuously.

[0154] (3) A method comprising injecting part of monomer (a1) or (a2) toa reaction vessel at the initial stage and then injecting the remnant ofmonomer (a1) or (a2) and the other monomers to a reaction vesselcontinuously.

[0155] (4) A method comprising injecting part of monomer (a1) or (a2)and part of the other monomers to a reaction vessel at the initialstage, and then injecting the remnant of monomer (a1) or (a2) and theremnant of the other monomers to a reaction vessel in several portions,respectively by turns.

[0156] Further, by varying the injection speed of each monomer to areaction vessel continuously or gradationally and changing the massratio of each injected monomer per time continuously or gradationally, acopolymer mixture containing each constituent unit differing in thecontent in the copolymer may be synthesized in the polymerizationreaction system. In addition, a radical polymerization initiator may beplaced in a reaction vessel at the initial stage, or may be addeddropwise to a reaction vessel, and these methods may be used combinedlyaccording to need.

[0157] For controlling the molecular weight of the product polymer (A),(B) or (G), a chain transfer agent may be used. Suitable as the chaintransfer agent are conventional hydrophilic chain transfer agents, forexample, thiol type chain transfer agents such as mercaptoethanol,thioglycerol, thioglycolic acid, 3-mercaptopropionic acid, thiomalicacid and 2-mercaptoethane sulfonic acid: secondary alcohol such asisopropyl alcohol: lower oxides such as phosphorous acid,hypophosphorous acid and salts thereof (for example, sodiumhypophosphorate and potassium hypophosphorate), sulfurous acid, hydrogensulfite, dithionic acid, (meth)bisulfurous acid and salts thereof(forexample, sodium sulfite, sodium hydrogen sulfite, sodium dithionite andsodium (meth)bisulfite), and salts thereof. Further, the use ofhydrophobic chain transfer agent is effective for improvement in cementcomposition viscosity. Suitable as the hydrophobic chain transfer agentare thiol type chain transfer agents having a hydrocarbon groupcontaining 3 or more carbon atoms such as butanethiol, octanethiol,decanethiol, dodecanethiol, hexadecanethiol, octadecanethiol, cyclohexylmercaptan, thiophenol, thioglycolic octyl, and 3-mercaptopropionicoctyl. It is also possible to use two or more chain transfer agentscombinedly and to use a hydrophilic chain transfer agent and hydrophobicchain transfer agent combinedly. Further, the molecular weight of thepolymer can also be controlled effectively by using, as the monomer (g),a monomer highly active in chain transfer, for example(meth)allylsulfonic acid (or a salt thereof).

[0158] For obtaining the polymer (A), (B) or (G) with a predeterminedmolecular weight with good reproducibility in the above polymerization,it is necessary that the polymerization reaction proceed in a stablemanner. Therefore, in the case of solution polymerization, the dissolvedoxygen concentration in the solvent employed at 25° C. is preferably notmore than 5 ppm, more preferably 0.01 to 4 ppm, still more preferably0.01 to 2 ppm, most preferably 0.01 to 1 ppm. When the addition of themonomers to the solvent is followed by purging with nitrogen or thelike, it is preferable that the dissolved oxygen concentration in thesystem, including the monomers, be within the above range.

[0159] The adjustment of the dissolved oxygen concentration in the abovesolvent may be carried out in the polymerization vessel or by using thesolvent adjusted in advance with respect to the dissolved oxygencontent. Suitable as the method of eliminating oxygen in solvents arethe following methods (1) to (5):

[0160] (1) A closed vessel containing the solvent is charged with aninert gas, such as nitrogen, under pressure, and the pressure within theclosed vessel is then reduced to thereby reduce the partial pressure ofoxygen in the solvent. The pressure within the closed vessel may bereduced in a nitrogen stream.

[0161] (2) The gaseous phase in a vessel containing the solvent isreplaced with an inert gas, such as nitrogen, and the liquid phase isstirred vigorously for a sufficiently long period of time.

[0162] (3) The solvent placed in a vessel is bubbled with an inert gas,such as nitrogen, for a sufficiently long period of time.

[0163] (4) The solvent is once boiled and then cooled in an inert gas(e.g. nitrogen) atmosphere.

[0164] (5) The relevant piping is provided with a static mixer, and thesolvent is admixed with an inert gas, such as nitrogen, in the course oftransfer to the polymerization vessel through the piping.

[0165] Each polymer obtained in the above manner, as such, can be usedas a main component of the cement admixture. If necessary, the polymermay be used after neutralization with an alkaline substance. Suitable asthe alkaline substance are inorganic salts such as the hydroxides orcarbonates of monovalent metals or divalent metals; ammonia; and organicamines. If necessary, the polymer concentration may be adjusted aftercompletion of the reaction. In cases where the constituent unit (III)derived from an unsaturated monocarboxylic acid ester monomer (c), whichis one of the essential constituent units in the polymer (A2), (C) or(G), includes an acrylic acid ester monomer-derived constituent unit, itis preferred that the polymerization be carried out in a weakly acidicto neutral pH range (pH 4 to 7) and, after completion of thepolymerization reaction, too, the pH be adjusted to 4 to 7 so that theester bond moiety can be prevented from being hydrolyzed. On the otherhand, it is also possible to use an unsaturated monocarboxylic acidester monomer (c), which provides the constituent unit (III), in lieu ofthe unsaturated monocarboxylic acid monomer (b), which provides theconstituent unit (II), in producing the polymer (A2), (C) or (G) and,after carrying out the copolymerization reaction, adjust the pH tothereby partially hydrolyze the ester bond moiety of the constituentunit (III) derived from an unsaturated monocarboxylic acid ester monomer(c)and thus introduce the constituent unit (II) derived from anunsaturated monocarboxylic acid monomer (b) into the polymer. Since thecommercially available unsaturated monocarboxylic acid ester monomers(c) generally contain the corresponding unsaturated monocarboxylic acidmonomers (b) in slight amounts, the acid value of the polymer, whenmeasured, is not always equal to 0 (zero) even when the polymerizationis carried out under conditions such that the ester bond moiety will notbe hydrolyzed during polymerization reaction.

[0166] The above polymers (A), (B) and (G) preferably have a weightaverage molecular weight of 1,000 to 500,000 as determined be gelpermeation chromatography (hereinafter referred to as “GPC”) on thepolyethylene glycol equivalent basis. By selecting such a weight averagemolecular weight range, it becomes possible to obtain cement admixturescapable of manifesting higher levels of dispersing ability. Morepreferably, the molecular weight is not less than 5,000 but not morethan 300,000, still more preferably not less than 10,000 but not morethan 150,000. The range of the molecular weight is more preferably 5000to 300000, still more preferably 10000 to 150000.

[0167] In the cement admixtures (1) to (4) according to the presentinvention, the ratio between the polymers (A) and (B), namely the mixingratio (polymer (A)/polymer (B)) (% by mass), is 1 to 99/99 to 1,preferably 5 to 95/95 to 5, more preferably 10 to 90/90 to 10, althoughthe optimal ratio may vary according to the performance characteristicbalances of the polymers combinedly used.

[0168] Two or more polymer (A) species and/or two or more polymer (B)species may combinedly be used. Suitable as such combinations of polymerspecies of each polymer are combinations of two or more polymer speciesdiffering in constituent unit(s); combinations of two or more polymerspecies identical in constituent units but differing in constituent unitcontents; combinations of two or more polymer species differing in themean addition number m of moles of the oxyalkylene group(s) in theunsaturated (poly)alkylene glycol ether monomer (a1) represented by theabove general formula (1), which monomer gives one of the essentialconstituent units in the polymer (A1) or (C); and combinations of two ormore polymer species differing in the mean addition number n of moles ofthe oxyalkylene group(s) in the unsaturated (poly)alkylene glycol ethermonomer (a2) represented by the above general formula (2), which monomergives one of the essential constituent units in the polymer (A2) or(A3).

[0169] In the cement admixture (5) according to the present invention,the ratio between the polymers (G) and (B5), namely the mixing ratio(polymer (G)/polymer (B5)) (% by mass), is 1 to 99/99 to 1, preferably 5to 95/95 to 5, more preferably 10 to 90/90 to 10, although the optimalratio may vary according to the performance characteristic balances ofthe polymers combinedly used. Two or more polymer (G) species and/or twoor more polymer (B5) species may combinedly be used. Suitable as suchcombinations of polymer species of each polymer are, for example,combinations of two or more polymer species differing in constituentunit(s); combinations of two or more polymer species identical inconstituent units but differing in constituent unit contents; andcombinations of two or more polymer species differing in the meanaddition number n of moles of the oxyalkylene group(s) in theunsaturated (poly)alkylene glycol ether monomer (a2) represented by theabove general formula (2), which monomer gives one of the essentialconstituent units in the polymer (G).

[0170] The cement admixture of this invention preferably comprises anon-polymerizable (poly)alkylene glycol (P) not containing an alkenylgroup, in addition to the polymer (A) or (B) as an essentialcomstituent.

[0171] The following polymerization reaction can be carried out using,as a starting material, a composition which comprises a byproduct(poly)alkylene glycol (P) in addition to a main product monomer (a1) or(a2) in producing the unsaturated (poly)alkylene glycol ether monomer(a1) or (a2). As a result, a cement admixture comprising anon-polymerizable (poly)alkylene glycol (P), in addition to the polymer(A)or (G) as an essential constituent, can be obtained. Further, in amonomer composition, used for polymerization reaction, comprising amonomer (a1) or (a2), and (poly)alkylene glycol (P), the suitableproportion of the (poly)alkylene glycol (P) is not less than 0.5% bymass relative to the monomer (a1) or (a2). In order to decrease theproportion of the byproduct (poly)alkylene glycol (P), a long time isneeded for conducting dehydration process to remove an impuritycomprising an active hydrogen such as water existing in variousmaterials used for addition reaction of an alkylene oxide such as anunsaturated alcohol, at the wall face of the reaction apparatus or inthe gas phase, from the reaction system and further, purificationprocess for removing (poly)alkylene glycol (P) after completion ofaddition reaction of an alkylene oxide is required, hence theproductivity of the monomer (a1) or (a2) unfavorably decreases. On theother hand, when the proportion of the (poly)alkylene glycol (P)relative to the monomer (a1) or (a2) exceeds 100% by mass, the monomerconcentration decreases during polymerization reaction, hence themolecular weight of the polymer (A) or (G) unfavorably decreases. Thus,the lower limit of the proportion is preferably not less than 1% bymass, more preferably not less than 1.5% by mass, still more preferablynot less than 2% by mass, most preferably not less than 2.5% by mass. Onthe other hand, the upper limit of the proportion is preferably not morethan 80% by mass, more preferably not more than 50% by mass, still morepreferably not more than 30% by mass, most preferably not more than 20%by mass. The suitable ranges of the proportion may be 0.5 to 100% bymass, 1 to 80% by mass, 1.5 to 50% by mass, 2 to 30% by mass, and 2.5 to20% by mass.

[0172] The proportion of (poly)alkylene glycol (P) relative to thepolymer (A) or (B) varies depending on the proportion of an unsaturated(poly)alkylene glycol ether monomer (a1) or (a2) in a monomercomposition used for polymerization reaction and the polymerization rateof each monomer. However, the lower limit of the proportion ispreferably not less than 1% by mass, more preferably not less than 1.5%by mass, still more preferably not less than 2% by mass, most preferablynot less than 2.5% by mass. On the other hand, the upper limit of theproportion is preferably not more than 50% by mass, more preferably notmore than 40% by mass, still more preferably not more than 30% by mass,most preferably not more than 20% by mass. The suitable ranges of theproportion may be 1 to 50% by mass, 1.5 to 40% by mass, 2 to 30% bymass, and 2.5 to 20% by mass.

[0173] After completion of producing an unsaturated (poly)alkyleneglycol ether monomer (a1) or (a2), (poly)alkylene glycol (P) separatelysynthesized may be added within the range of the above proportion suchthat the decrease in molecular weight of polymer (A) or (G) owing to themonomer concentration decrease during polymerization reaction can not begenerated. Further, after completion of polymerization reaction,(poly)alkylene glycol (P) separately synthesized may be added. Thestructures of (poly)alkylene glycol (P) added and (poly)alkylene glycol(P) contained as a byproduct may be the same or different. Thus, thecement admixture of the present invention may comprise two or morespecies of (poly)alkylene glycol (P).

[0174] When (poly)alkylene glycol (P) which is a byproduct in producingan unsaturated (poly)alkylene glycol ether monomer (a1) or (a2) is used,the number of carbon atoms contained in oxyalkylene group of the(poly)alkylene glycol (P) corresponds to an alkylene oxide used forproducing a monomer (a1) or (a2). On the other hand, when (poly)alkyleneglycol (P) separately synthesized is added, the number is appropriately2 to 18, preferably 2 to 8, more preferably 2 to 4. In the case ofalkylene oxide adducts derived from two or more species optionallyselected from among ethylene oxide, propylene oxide, butylene oxide,styrene oxide and the like, the mode of addition may be of the random,block and/or alternating type, for instance. For securing a balancebetween the hydrophilicity and hydrophobicity, it is preferred that theoxyalkylene group comprises the oxyethylene group as an essentialconstituent, with the oxyethylene group preferably accounting for atleast 50 mole percent, more preferably at least 90 mole percent.

[0175] When (poly)alkylene glycol (P) which is a byproduct in producingan unsaturated (poly)alkylene glycol ether monomer (a1) or (a2) is used,the terminal group of the (poly)alkylene glycol (P) depends on theproduction method of a monomer (a1) or (a2) and generally corresponds toR² in the above general formula (1) or (2), namely is a hydrogen atom ora hydrocarbon group containing 1 to 30 carbon atoms. The specificexamples thereof are those mentioned for R² in the above general formula(1) or (2), however, a hydrogen atom(s) generally binds at one terminalor both terminals. On the other hand, when (poly)alkylene glycol (P)separately synthesized is added, the terminal group of the(poly)alkylene glycol (P) does not depend on the production method of amonomer (a1) or (a2), however, preferably corresponds to R² in the abovegeneral formula (1) or (2), namely is preferably a hydrogen atom or ahydrocarbon group containing 1 to 30 carbon atoms. As for the(poly)alkylene glycol (P) containing hydrogen atoms at both terminalsand produced from water as a starting material, specifically, there aremay be mentioned (poly)ethylene glycol, (poly)propylene glycol,(poly)ethylene(poly)propylene glycol and (poly)ethylene(poly)butyleneglycol. However, since a water-soluble compound is preferred,(poly)ethylene glycol or (poly)ethylene(poly)propylene glycol is morepreferred and (poly)ethylene glycol is still more preferred.

[0176] When (poly)alkylene glycol (P) which is a byproduct forproduction of a monomer (a1) or (a2) is used, the weight averagemolecular weight of (poly)alkylene glycol (P) depends on the productionconditions of monomer (a1) or (a2), in particular the mean additionnumber m or n of moles of oxyalkylene group(s) but generally is 50 to50000. On the other hand, when (poly)alkylene glycol (P) separatelysynthesized is added, the range of the weight average molecular weightis preferably 100 to 200000, more preferably 500 to 100000, still morepreferably 1000 to 50000.

[0177] Preferably, the cement admixture according to the presentinvention comprises an unsaturated (poly)alkylene glycol ether monomer(a1) or (a2), in addition to the polymer (A) or (G) as an essentialconstituent. In a preferred embodiment, the cement admixture (1) furthercomprises the above unsaturated (poly)alkylene glycol ether monomer(a1), and the cement admixtures (2) to (5) further comprise the aboveunsaturated (poly)alkylene glycol ether monomer (a2).

[0178] Since the unsaturated (poly)alkylene glycol ether monomer (a1) or(a2) is not polymerizable by itself, it tends to remain after completionof polymerization reaction. Thus, for decreasing the level of themonomer (a1) or (a2) under the detectable limit value, it is necessaryto increase the amount of an initiator, further add an initiator atlatter stage of polymerization, or prolong a polymerization reactiontime. However, since it becomes difficult to control the molecularweight and/or the productivity tends to decrease, it is preferable tostop the polymerization reaction while the monomer (a1) or (a2) remains.On the other hand, in the case where the proportion of monomer (a1) or(a2) relative to the polymer (A) or (G) exceeds 100% by mass, thedispersing ability of the cement admixture for cement deterioratesunfavorably. Thus, the lower limit of the proportion of monomer (a1) or(a2) relative to the polymer (A) or (G) is suitably not less than 0.5%by mass, preferably not less than 1% by mass, more preferably not lessthan 2% by mass, still more preferably not less than 3% by mass, andmost preferably not less than 4% by mass. On the other hand, the upperlimit of the proportion is suitably not more than 100% by mass,preferably not more than 90% by mass, more preferably not more than 80%by mass, still more preferably not more than 70% by mass, and mostpreferably not more than 60% by mass. As for the suitable range of theproportion, there may be mentioned 0.5 to 100% by mass, 1 to 90% bymass, 2 to 80% by mass, 3 to 70% by mass, and 4 to 60% by mass. Aftercompletion of producing the polymer (A) or (G), the monomer (a1) or (a2)may be added within the range of the above proportion such that thedecrease in dispersing ability for cement cannot be induced. Thestructures of the monomer (a1) or (a2) added and the monomer (a1) or(a2) remained as an unreacted monomer may be the same or different.

[0179] The-preferred method for producing the polymer (A) or (G)comprises carrying out polymerization reaction using a composition whichcomprises a non-polymerizable (poly)alkylene glycol (P) not containingan alkenyl group as a starting material, in addition to a monomercomposition comprising an unsaturated (poly)alkylene glycol ethermonomer (a1) or (a2) as an essential constituent, and stoping thepolymerization reaction while the monomer (a1) or (a2) remains. In thismanner, the cement admixture of the invention comprising a monomer (a1)or (a2), and (poly)alkylene glycol (P) in addition to the polymer (A) or(G) can be obtained easily. The composition which comprises anon-polymerizable (poly)alkylene glycol (P) not containing an alkenylgroup, in addition to an unsaturated (poly)alkylene glycol ether monomer(a1) or (a2) can be obtained by the above-mentioned method for producingan unsaturated (poly)alkylene glycol ether monomer (a1) or (a2).

[0180] The cement admixtures (1) to (5) according to the inventioncomprises two polymers, namely (1) the polymers (A1) and (B1), (2) thepolymers (A2) and (B2), (3) the polymers (A3) and (B3), (4) the polymers(A3) and (B4) and (5) the polymers (G) and (B5), as essentialconstituents. Each polymer may be used, as a main constituent of thecement admixture, in the form of an aqueous solution, or in the form ofa powder prepared by neutralizing with the hydroxide of a divalent metalsuch as calcium or magnesium to give a polyvalent metal salt, followedby drying, or by causing the polymer or salt to be carried on aninorganic powder such as a fine silicic powder, followed by drying.

[0181] The cement admixtures (1) to (5) according to the invention canbe used in various hydraulic materials, namely in cement and otherhydraulic materials then cement, for example gypsum. Preferred examplesof the hydraulic composition comprising a hydraulic material, water andthe cement admixture according to the invention, if necessary togetherwith a fine aggregate (e.g. sand) or a coarse aggregate (e.g. crushedstone), are cement paste, mortar, concrete and plaster.

[0182] Among the hydraulic compositions mentioned above, cementcompositions in which cement is used as the hydraulic material are incommonest use. Such cement compositions comprise the above-mentionedcement admixture, cement and water as essential constituents. Suchcement compositions also constitute an aspect of the present invention.

[0183] Suited for use as the cement in the cement composition accordingto the invention are portland cement species (ordinary,high-early-strength, ultra high-early-strength, moderate heat, sulfatepersisting, and low alkali grades thereof), various blended cementspecies (blast furnace slag cement, silica cement, fly ash cement),white portland cement, alumina cement, ultra rapid hardening cement (oneclinker ultra rapid hardening cement, two clinker ultra rapid hardeningcement, magnesium phosphate cement), grouting cement, oil-well cement,lower calorific value cement (lower calorific value blast furnace slagcement, fly ash-mixed lower calorific value blast furnace slag cement,high belite cement), ultrahigh strength cement, cement-based hardeningmaterials, and economical cement (cement produced by using at least oneof municipal refuse incineration ash and sewage sludge incineration ashas a material). Fine powders such as blast furnace slag, fly ash, cinderash, clinker ash, husk ash, silica fume, silica powder and limestonepowder, and gypsum may further be added. Usable as the aggregate aregravel, crushed stone, water granulated blast furnace slag, recycledconcrete aggregate and, further, fireproof aggregates such as silicastone-based, clay-based, zircon-based, high alumina, siliconcarbide-based, graphite-based, chrome-based, chrome-magnesite, andmagnesia-based ones.

[0184] As for the unit water amount, the amount of cement and thewater/cement ratio in each cubic meter of the cement compositionaccording to the invention, the unit water amount of 100 to 185 kg/m³,the amount of cement as used of 250 to 800 kg/m³, and the water/cementratio (mass ratio) of 0.1 to 0.7 are preferred. More preferably, theunit water amount of 120 to 175 kg/M³, the amount of cement as used of270 to 800 kg/m³, and the water/cement ratio (mass ratio) of 0.2 to 0.65are recommended for wide use in poor to rich mixtures, inclusive of highstrength concrete with a high unit cement amount to poor concrete withthe unit cement amount of 300 kg/m³ or lower.

[0185] The level of addition of the cement admixtures (1) to (5)according to the invention in the cement composition according to theinvention is preferably 0.01 to 5.0% by mass based on the mass of cementwhen it is used in mortar or concrete, for instance, in which hydrauliccement is used. By this addition, various favorable effects, such asreduction in unit water amount, increase in strength and improvement indurability, are realized. When the above addition level is lower than0.01%, the performance characteristics may become insufficient.Conversely, when it exceeds 5.0%, the effects will substantially reachthe peak and this may be disadvantageous from the economical viewpoint.A more preferred addition level is not lower than 0.02% but not higherthan 2.0%, still more preferably not lower than 0.05% but not higherthan 1.0%. Thus, recommendably, the admixture is added at such anaddition level. The range of the addition level is more preferably 0.02to 2.0%, still more preferably 0.05 to 1.0%.

[0186] The cement admixtures (1) to (5) of the present invention may beused in combination with one or plural conventional cement dispersants.When such a conventional cement dispersant(s) is (are) used, the mixingratio between the cement admixture of the invention and the conventionalcement dispersant(s) is preferably 1/99 to 99/1, more preferably 5/95 to95/5, still more preferably 10/90 to 90/10, although it cannot bespecified in a wholesale manner since it depends on the conventionalcement dispersant species employed, the formulation, the test conditionsand so forth.

[0187] Suited for combined use as the conventional cement dispersant isa sulfonic acid type dispersant (S) containing a sulfonic acid group inthe molecule. By using a sulfonic acid type dispersant (S) containing asulfonic acid group in the molecule in combination, a cement admixturehaving high dispersion retaining ability, and showing a stabledispersing ability not depending on a cement brand or lot number, can beobtained. A sulfonic acid type dispersant (S) exhibits dispersingability for cement due to the mainly sulfonic acid group-inducedelectrostatic repulsion. Various conventional sulfonic acid typedispersants may be used but a compound containing an aromatic group inthe molecule is preferred. Specifically, there may be mentioned(poly)alkyl aryl sulfonic acid salt type such as naphthalenesulfonicacid-formaldehyde condensates, methylnaphthalenesulfonicacid-formaldehyde condensates, and anthracenesulfonic acid-formaldehydecondensates; melamineformalin resin sulfonic acid salt type such asmelaminesulfonic acid-formaldehyde condensates; aromatic aminosulfonicacid salt type such as aminoarylsulfonic acid-phenol-formaldehydecondensates; ligninsulfonic acid salt type such as ligninsulfonic acidsalts and modified ligninsulfonic acid salts; polystyrenesulfonic acidsalt type, and like sulfonic acid type dispersants. When thewater/cement ratio in concrete is high, ligninsulfonic acid salt typedispersants are preferably used. On the other hand, when thewater/cement ratio in concrete is at middle level, (poly)alkyl arylsulfonic acid salt type, melamineformalin resin sulfonic acid salt type,aromatic aminosulfonic acid salt type or polystyrenesulfonic acid salttype dispersants are preferably used, which have the higher dispersionability. Further, two or more sulfonic acid type dispersants (S)containing a sulfonic acid group in the molecule may be used incombination.

[0188] An aqueous solution in which each polymer component in the cementadmixture of the invention (the polymer (A), (B) and (G)) and a sulfonicacid type dispersant (S) containing a sulfonic acid group in themolecule are dissolved together, prior to mixing a cement compositionmay be added to a cement. Further, aqueous solutions in which eachcomponent is dissolved respectively may be added respectively to acement during mixing a cement composition, each component prepared in apowder form may be added to a cement during mixing a cement composition,and any aqueous solution and/or any component prepared in a powder formmay be added to a cement during mixing a cement composition.

[0189] The ratio of the cement admixtures (1) to (5) and a sulfonic acidtype dispersant (S) containing a sulfonic acid group in the molecule,namely (total content of each polymer component (polymer (A), (B), or(G)) in any of the cement admixtures (1) to (5)/sulfonic acid typedispersant (S)) (% by mass) varies depending on the performance balancebetween the cement admixture of the invention and sulfonic acid typedispersant (S) containing a sulfonic acid group in the molecule used incombination, however, it is preferably 1 to 99/99 to 1, more preferably5 to 95/95 to 5, still more preferably 10 to 90/90 to 10.

[0190] The addition proportion of the cement admixture which comprisesas essential constituents, the cement admixtures (1) to (5) according tothe present invention and a sulfonic acid type dispersant (S) containinga sulfonic acid group in the molecule to cement, when they applied tomortar or concrete using hydraulic cement, is preferably 0.01 to 10.0%on cement mass basis. It is more preferably 0.02 to 5.0%, still morepreferably 0.05 to 2.0%.

[0191] Further, when the water/cement ratio is comparatively high andespecially high dispersing ability is not required, a cement admixture(hereinafter referred to as cement admixture (6)) comprising, asessential constituents, the polymer (A) or (G), and a sulfonic acid typedispersant (S) containing a sulfonic acid group in the molecule, issuitable.

[0192] The cement admixture (6) preferably comprises a non-polymerizable(poly)alkylene glycol (P) not containing an alkenyl group, in additionto the polymer (A) or (G) as an essential constituent. Detailedexplanations for (poly)alkylene glycol (P), for example, the ratio of(poly)alkylene glycol (P) relative to the polymer (A) or (G) are thosespecifically mentioned for the above cement admixtures (1) to (5).

[0193] The cement admixture (6) preferably further comprises anunsaturated (poly)alkylene glycol ether monomer (a1) or (a2), inaddition to the polymer (A) or (G) as an essential constituent. Detailedexplanations for an unsaturated (poly)alkylene glycol ether monomer (a1)or (a2), for example, the ratio of an unsaturated (poly)alkylene glycolether monomer (a1) or (a2) relative to the polymer (A) or (G) are thosespecifically mentioned for the above cement admixtures (1) to (5).

[0194] The cement admixture (6) preferably further comprises a monomer(a1) or (a2), and (poly)alkylene glycol (P), in addition to the polymer(A) or (G) as an essential constituent. The production method of acement admixture comprising a monomer (a1) or (a2), and (poly)alkyleneglycol (P), in addition to the polymer (A) or (G) as an essentialconstituent and so on, are those specifically mentioned for the abovecement admixtures (1) to (5).

[0195] In the cement admixture (6), the ratio of polymer (A) or (G), anda sulfonic acid type dispersant (S) containing a sulfonic acid group inthe molecule, namely the addition proportion (polymer (A) or(G)/sulfonic acid type dispersant (S)) (% by mass) varies depending onthe performance characteristic balance between the polymer (A) or (G),and sulfonic acid type dispersant (S) containing a sulfonic acid groupin the molecule used in combination, however, it is preferably 1 to99/99 to 1, more preferably 5 to 95/95 to 5, still more preferably 10 to90/90 to 10. In addition, two or more of the polymer (A), (G), andsulfonic acid type dispersant (S) containing a sulfonic acid group inthe molecule respectively, may be used in combination.

[0196] The addition proportion of the cement admixture (6) to cement,when they applied to mortar or concrete using hydraulic cement, ispreferably 0.01 to 10.0% on cement mass basis. It is more preferably0.02 to 5.0%, still more preferably 0.05 to 2.0%.

[0197] Further, the cement admixture (6) may be used for varioushydraulic materials. A cement composition comprising, as essentialconstitutes, the cement admixture (6), cement and water constitutes oneaspect of the present invention, and usable cement and so on are thosespecifically mentioned for the above cement admixtures (1) to (5).

[0198] The cement composition according to the invention is effective inready mixed concrete, concrete for secondary concrete products (precastconcrete), centrifugal molded concrete, vibrating compacted concrete,steam cured concrete, concrete for spraying and the like and, further,it is effective also in mortar and concrete species required to havehigh flowability, such as medium flowing concrete (concrete showing aslump value of 22 to 25 cm), high flowing concrete (concrete showing aslump value of not less than 25 cm and a slump flow value of 50 to 70cm), self-filling concrete and self-leveling materials.

[0199] The cement composition according to the invention may furthercomprise one or more of other known cement additives (ingredients) suchas listed below under (1) to (20):

[0200] (1) Water-soluble polymeric substances: unsaturated carboxylicacid polymers such as polyacrylic acid (sodium salt), polymethacrylicacid (sodium salt), polymaleic acid (sodium salt), and acrylicacid-maleic acid copolymer sodium salt; nonionic cellulose ethers suchas methylcellulose, ethylcellulose, hydroxymethylcellulose,hydroxyethylcellulose, carboxymethylcellulose, carboxyethylcellulose andhydroxypropylcellulose; polysaccharide derivatives derived fromalkylated or hydroxyalkylated derivatives of polysaccharides, such asmethylcellulose, ethylcellulose, hydroxyethylcellulose andhydroxypropylcellulose, by substitution of a part or all of hydroxylhydrogen atoms with a hydrophobic substituent comprising a hydrocarbonchain containing 8 to 40 carbon atoms as a partial structure and anionic hydrophilic substituent containing a sulfonic acid group or a saltthereof as a partial structure; yeast glucans, xanthan gum,β-1,3-glucans (linear or branched, e.g. curdlan, paramylon, pachyman,scleroglucan, rhamnalan) and like polysaccharides produced by microbialfermentation; polyacrylamide; polyvinyl alcohol; starch; starchphosphoric acid ester; sodium alginate; gelatin; amino-containingacrylic acid copolymers and quaternization products derived therefrom.

[0201] (2) Polymer emulsions: copolymers of various vinyl monomer suchas alkyl (meth)acrylates.

[0202] (3) Retarders: hydroxycarboxylic acids such as gluconic acid,glucoheptonic acid, arabonic acid, malic acid, citric acid, andinorganic or organic salts thereof such as sodium, potassium, calcium,magnesium, ammonium and triethanolamine salts; monosaccharides such asglucose, fructose, galactose, saccharose, xylose, apiose, ribose andinvert sugar, oligosaccharides such as disaccharides and trisaccharides,such oligosaccharides as dextrin, polysaccharides such as dextran, andother saccharides such as molasses containing these; sugar alcohols suchas sorbitol; magnesium silicofluoride; phosphoric acid and saltsthereof, or borate esters; aminocarboxylic acids and salts thereof;alkali-soluble proteins; humic acid; tannic acid; phenols; polyhydricalcohols such as glycerol; phosphonic acids and derivatives thereof,such as aminotri(methylenephosphonic acid),1-hydroxyethylidene-1,1-diphosphonic acid,ethylenediaminetetra(methylenephosphonic acid),diethylenetriaminepenta(methylenephosphonic acid), and alkali metal oralkaline earth metal salts thereof, etc.

[0203] (4) Early strengthening agents/accelerators: soluble calciumsalts such as calcium chloride, calcium nitrite, calcium nitrate,calcium bromide and calcium iodide; chlorides such as iron chloride andmagnesium chloride; sulfate salts; potassium hydroxide; sodiumhydroxide; carbonate salts; thiosulfate salts; formic acid and formatesalts such as calcium formate; alkanolamines; alumina cement; calciumaluminosilicate, etc.

[0204] (5) Mineral oil-based antifoaming agents: kerosene, liquidparaffin, etc.

[0205] (6) Fat- or oil-based antifoaming agents: animal or vegetableoils, sesame oil, castor oil, alkylene oxide adducts derived therefrom,etc.

[0206] (7) Fatty acid-based antifoaming agents: oleic acid, stearicacid, and alkylene oxide adducts derived therefrom, etc.

[0207] (8) Fatty acid ester-based antifoaming agents: glycerolmonoricinolate, alkenylsuccinic acid derivatives, sorbitol monolaurate,sorbitol trioleate, natural waxes, etc.

[0208] (9) Oxyalkylene type antifoaming agents: polyoxyalkylenes such as(poly)oxyethylene(poly)oxypropylene adducts; (poly)oxyalkyl ethers suchas diethylene glycol heptyl ether, polyoxyethylene oleyl ether,polyoxypropylene butyl ether, polyoxyethylenepolyoxypropylene2-ethylhexyl ether, and higher (C₁₂-C₁₄) alcohol-oxyethyleneoxypropyleneadducts; (poly)oxyalkylene (alkyl)aryl ethers such as polyoxypropylenephenyl ether and polyoxyethylene nonylphenyl ether; acetylene ethersproduced by addition polymerization of an alkylene oxide onto anacetylene alcohol such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol,2,5-dimethyl-3-hexyne-2,5-diol or 3-methyl-1-butyn-3-ol;(poly)oxyalkylene fatty acid esters such as diethylene glycol oleate,diethylene glycol laurate and ethylene glycol distearate;(poly)oxyalkylenesorbitan fatty acid esters such aspolyoxyethylenesorbitan monolaurate and polyoxyethylenesorbitantrioleate; (poly)oxyalkylene alkyl(aryl) ether sulfate ester salts suchas polyoxypropylene methyl ether sulfate sodium salt and polyoxyethylenedodecylphenyl ether sulfate sodium salt; (poly)oxyalkylenealkylphosphate esters such as polyoxyethylene stearylphosphate;(poly)oxyalkylenealkylamines such as polyoxyethylenelaurylamine;polyoxyalkyleneamides, etc.

[0209] (10) Alcohol-based antifoaming agents: octyl alcohol, hexadecylalcohol, acetylene alcohols, glycols, etc.

[0210] (11) Amide-based antifoaming agents: acrylate polyamines, etc.

[0211] (12) Phosphate ester-based antifoaming agents: tributylphosphate, sodium octylphosphate, etc.

[0212] (13) Metal salt-based antifoaming agents: aluminum stearate,calcium oleate, etc.

[0213] (14) Silicone-based antifoaming agents: diemthylsilicone oil,silicone paste, silicone emulsions, organic group-modified polysiloxanes(organosiloxanes such as dimethylpolysiloxane), fluorosilicone oils,etc.

[0214] (15) Air-entraining (AE) agents: resin soaps, saturated orunsaturated fatty acids, sodium hydroxystearate, lauryl sulfate, ABSs(alkylbenzenesulfonates), LASs (linear alkylbenzenesulfonates),alkanesulfonates, polyoxyethylene alkyl(phenyl) ethers, polyoxyethylenealkyl(phenyl) ether sulfate esters or salts thereof, polyoxyethylenealkyl(phenyl) ether phosphate esters or salts thereof, proteinicmaterials, alkenylsulfosuccinates, α-olefinsulfonates, etc.

[0215] (16) Other surfactants: polyalkylene oxide derivatives derivedfrom aliphatic monohydric alcohols containing 6 to 30 carbon atomswithin the molecule, such as octadecyl alcohol and stearyl alcohol,alicyclic monohydric alcohols containing 6 to 30 carbon atoms within themolecule, such as abietyl alcohol, monofunctional mercaptans containing6 to 30 carbon atoms within the molecule, such as dodecylmercaptan,alkylphenols containing 6 to 30 carbon atoms within the molecule, suchas nonylphenol, amines containing 6 to 30 carbon atoms within themolecule, such as dodecylamine, or carboxylic acids containing 6 to 30carbon atoms within the molecule, such as lauric acid and stearic acid,by addition of not less than 10 moles of an alkylene oxide(s) such asethylene oxide and/or propylene oxide; alkyldiphenyl ether sulfonic acidsalts in which two sulfo-containing phenyl groups, which may optionallyhave an alkyl group or alkoxy group as a substituent, is bonded viaether bonding; various anionic surfactants; various cationic surfactantssuch as alkylamine acetates and alkyltrimethylammonium chlorides;various nonionic surfactants; various amphoteric surfactants, etc.

[0216] (17) Waterproofing agents: fatty acids (salts), fatty acidesters, fats and oils, silicones, paraffins, asphalt, waxes, etc.

[0217] (18) Rust preventives: nitrite salts, phosphate salts, zincoxide, etc.

[0218] (19) Cracking reducing agents: polyoxyalkyl ethers etc.

[0219] (20) Expansive admixtures: ettringite type, coal-derived type,etc.

[0220] As other conventional cement additives (ingredients), there maybe mentioned cement wetting agents, thickening agents, separationreducing agents, flocculants, drying shrinkage reducing agents, strengthincreasing agents, self-leveling agents, rust preventives, colorants,antifungal agents and so on. It is also possible to combinedly use aplurality of the cement additives (constituents) mentioned above.

[0221] The following combinations 1) to 4) of constituents other thancement and water in the cement composition according to the inventionmay be mentioned as particularly preferred embodiments:

[0222] 1) Combination of (1) a cement admixture according to theinvention and (2) an oxyalkylene type antifoaming agent as two essentialconstituents. The proportion of the oxyalkylene type antifoaming agent(2) is preferably 0.01 to 10% by mass relative to the cement admixture(1).

[0223] 2) Combination of (1) a cement admixture according to theinvention and (2) a material separation reducing agent as two essentialconstituents. Usable as the material separation reducing agent arevarious thickening agents such as nonionic cellulose ethers, andcompounds containing, as partial structures, a hydrophobic substituentcomprising a hydrocarbon chain containing 4 to 30 carbon atoms and apolyoxyalkylene chain resulting from addition of 2 to 300 moles, onaverage, of an alkylene oxide(s) containing 2 to 18 carbon atoms, amongothers. The mixing ratio, by mass, between the cement admixture (1) andmaterial separation reducing agent (2) is preferably 10/90 to99.99/0.01, more preferably 50/50 to 99.9/0.1. Cement compositionscontaining this combination are suited for use as high flowing concrete,self-filling concrete and self-leveling compositions.

[0224] 3) Combination of (1) a cement admixture according to theinvention and (2) a retarder as two essential constituents. Usable asthe retarder are hydroxycarboxylic acids such as gluconic acid (salts)and citric acid (salts), saccharides such as glucose, sugar alcoholssuch as sorbitol, and phosphonic acids such asaminotri(methylenephosphonic acid), among others. The mixing ratio, bymass, between the cement admixture (1) and retarder (2) is preferably50/50 to 99.9/0.1, more preferably 70/30 to 99/1.

[0225] 4) Combination of (1) a cement admixture according to theinvention and (2) an accelerator as two essential constituents. Usableas the accelerator are soluble calcium salts such as calcium chloride,calcium nitrite and calcium nitrate, chlorides such as iron chloride andmagnesium chloride, thiosulfate salts, formic acid, and formate saltssuch as calcium formate, among others. The mixing ratio, by mass,between the cement admixture (1) and accelerator (2) is preferably 10/90to 99.9/0.1, more preferably 20/80 to 99/1.

[0226] The cement admixture of the present invention shows high cementdispersing ability at low addition levels, in particular capable ofdisplaying excellent initial dispersing ability and dispersion retainingability even in a high water reducing ratio range, and a cementcomposition in which this admixture is used. The cement compositioncomprising the cement admixture of the invention shows good flowabilityand can avoid troubles otherwise encountered in construction works.

BEST MODES FOR CARRYING OUT THE INVENTION EXAMPLES

[0227] The following examples illustrate the present invention morespecifically. They are, however, by no means limitative of the scope ofthe invention. In the examples, “%” denotes “% by mass” and “part(s)”means “part(s) by weight”, unless otherwise specified.

[0228] <Weight Average Molecular Weight Determination Conditions>

[0229] Apparatus: Waters LCM1 (product of Waters Corp.)

[0230] Detector: differential refractometer (RI) detector (Waters 410)(product of Waters Corp.)

[0231] Eluent: species: acetonitrile/0.05 M deionized water solution ofsodium acetate (40/60% by volume), adjusted to pH 6.0 with acetic acid

[0232] flow rate: 0.6 ml/min

[0233] Column: species: product of Tosoh Corp., TSK-GELG4000SWXL+G3000SWXL+G2000SWXL+GUARD COLUMN (each 7.8×300 mm, 6.0×40 mm)

[0234] temperature: 40° C.

[0235] Working curve: polyethylene glycol standards

[0236] <Determination Conditions of Conversion of Starting Monomer>

[0237] Apparatus: Borwin (product of JASCO Corp.)

[0238] Detector: differential refractometer (RI) detector (HITACHI 3350RI MONITOR) (product of Hitachi Corp.)

[0239] Eluent: species: acetonitrile/0.1% deionized water solution ofphosphoric acid (50/50% by volume)

[0240] flow rate: 1.0 ml/min

[0241] Column: species: product of Tosoh Corp., ODS-120T+ODS-80Ts (each4.6×250 mm)

[0242] temperature: 40° C.

[0243] <Determination Conditions of Production Amount ofNon-Polymerizable Polyalkylene Glycol not Containing an Alkenyl Group>

[0244] Apparatus: LC-10 (product of Shimadzu Corp.)

[0245] Detector: differential refractometer (RI) detector (HITACHI 3350RI MONITOR) (product of Hitachi Corp.)

[0246] Eluent: species: deionized water

[0247] flow rate: 1.5 ml/min

[0248] Column: species: product of Showa Denko Corp., Shodex GF-310(4.6×300 mm)

[0249] temperature: 40° C.

Production Example 1

[0250] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 277 parts of deionized water, and 400 partsof unsaturated polyalkylene glycol ether derived from3-methyl-3-buten-1-ol by addition of 50 moles, on average, of ethyleneoxide. After raising the temperature to 65° C., an aqueous hydrogenperoxide solution composed of 0.670 part of hydrogen peroxide and 12.73parts of deionized water was added thereto. Then, 58.4 parts of acrylicacid was added dropwise to the reaction vessel over 3 hours, and at thesame time, an aqueous solution prepared by dissolving 0.868 part ofL-ascorbic acid and 1.569 parts of 3-mercaptopropionic acid in 16.49parts of deionized water was added dropwise over 3.5 hours. Thereafter,the temperature was further maintained at 65° C. for 1 hour, andthereafter the polymerization reaction was finished. The polymerizablecomponent concentration (mass % concentration of all monomer componentsrelative to all raw materials) at the time of finish of thepolymerization reaction was 60%. The reaction mixture was thenneutralized to pH 7 with an aqueous solution of sodium hydroxide at atemperature not higher than the polymerization reaction temperature togive a polymer (A-1), corresponding to the polymer (A) according to thepresent invention, composed of an aqueous solution of the polymer havinga weight average molecular weight of 30,500. For the polymer obtained,the conversion (%) of each starting monomer, the composition ratio ofcopolymer (ratio of the constituent unit derived from each monomer)(% bymass), the composition ratio of copolymer (ratio of the constituent unitderived from each monomer) (mole %), and the carboxylic acid content(meq/g) calculated on the unneutralized polymer basis are shown in Table1.

Production Example 2

[0251] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 277 parts of deionized water, and 400 partsof unsaturated polyalkylene glycol ether derived from methallyl alcoholby addition of 50 moles, on average, of ethylene oxide. After raisingthe temperature to 65° C., an aqueous hydrogen peroxide solutioncomposed of 0.630 part of hydrogen peroxide and 11.98 parts of deionizedwater was added thereto. Then, 54.1 parts of acrylic acid was addeddropwise to the reaction vessel over 3 hours, and at the same time, anaqueous solution prepared by dissolving 0.816 part of L-ascorbic acidand 1.968 parts of 3-mercaptopropionic acid in 15.51 parts of deionizedwater was added dropwise over 3.5 hours. Thereafter, the temperature wasfurther maintained at 65° C. for 1 hour, and thereafter thepolymerization reaction was finished. The polymerizable componentconcentration (mass % concentration of all monomer components relativeto all raw materials) at the time of finish of the polymerizationreaction was 60%. The reaction mixture was then neutralized to pH 7 withan aqueous solution of sodium hydroxide at a temperature not higher thanthe polymerization reaction temperature to give a polymer (A-2),corresponding to the polymer (A) according to the present invention,composed of an aqueous solution of the polymer having a weight averagemolecular weight of 28,000. For the polymer obtained, the conversion (%)of each starting monomer, the composition ratio of copolymer (% bymass), the composition ratio of copolymer (mole %), and the carboxylicacid content (meq/g) calculated on the unneutralized polymer basis areshown in Table 1.

Production Example 3

[0252] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 220 parts of deionized water, and 400 partsof unsaturated polyalkylene glycol ether derived from allyl alcohol byaddition of 75 moles, on average, of ethylene oxide. After raising thetemperature to 80° C., an aqueous hydrogen peroxide solution composed of1.610 parts of hydrogen peroxide and 30.59 parts of deionized water wasadded thereto. Then, 34.0 parts of acrylic acid was added dropwise tothe reaction vessel over 3 hours, and at the same time, an aqueoussolution prepared by dissolving 2.085 parts of L-ascorbic acid and 0.628part of 3-mercaptopropionic acid in 39.62 parts of deionized water wasadded dropwise over 3.5 hours. Thereafter, the temperature was furthermaintained at 80° C. for 1 hour, and thereafter the polymerizationreaction was finished. The polymerizable component concentration (mass %concentration of all monomer components relative to all raw materials)at the time of finish of the polymerization reaction was 60%. Thereaction mixture was then neutralized to pH 7 with an aqueous solutionof sodium hydroxide at a temperature not higher than the polymerizationreaction temperature to give a polymer (A-3), corresponding to thepolymer (A) according to the present invention, composed of an aqueoussolution of the polymer having a weight average molecular weight of30,000. For the polymer obtained, the conversion (%) of each startingmonomer, the composition ratio of copolymer (% by mass), the compositionratio of copolymer (mole %), and the carboxylic acid content (meq/g)calculated on the unneutralized polymer basis are shown in Table 1.

Production Example 4

[0253] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 278 parts of deionized water, and 400 partsof unsaturated polyalkylene glycol ether derived from3-methyl-3-buten-1-ol by addition of 25 moles, on average, of ethyleneoxide. After raising the temperature to 65° C., an aqueous hydrogenperoxide solution composed of 0.627 part of hydrogen peroxide and 11.91parts of deionized water was added thereto. Then, 17.7 parts of acrylicacid and 39.3 parts of 2-hydroxyethyl acrylate were added dropwise tothe reaction vessel over 3 hours, and at the same time, an aqueoussolution prepared by dissolving 0.812 part of L-ascorbic acid and 1.468parts of 3-mercaptopropionic acid in 15.43 parts of deionized water wasadded dropwise over 3.5 hours. Thereafter, the temperature was furthermaintained at 65° C. for 1 hour, and thereafter the polymerizationreaction was finished. The polymerizable component concentration (mass %concentration of all monomer components relative to all raw materials)at the time of finish of the polymerization reaction was 60%. Thereaction mixture was then neutralized to pH 7 with an aqueous solutionof sodium hydroxide at a temperature not higher than the polymerizationreaction temperature to give a polymer (C-1), corresponding to thepolymer (C) according to the present invention, composed of an aqueoussolution of the polymer having a weight average molecular weight of29,000. For the polymer obtained, the conversion (%) of each startingmonomer, the composition ratio of copolymer (% by mass), the compositionratio of copolymer (mole %), and the carboxylic acid content (meq/g)calculated on the unneutralized polymer basis are shown in Table 1.

Production Example 5

[0254] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 279 parts of deionized water, and 400 partsof unsaturated polyalkylene glycol ether derived from3-methyl-3-buten-1-ol by addition of 25 moles, on average, of ethyleneoxide. After raising the temperature to 65° C., an aqueous hydrogenperoxide solution composed of 0.605 part of hydrogen peroxide and 11.50parts of deionized water was added thereto. Then, 17.7 parts of acrylicacid and 39.3 parts of butyl acrylate were added dropwise to thereaction vessel over 3 hours, and at the same time, an aqueous solutionprepared by dissolving 0.784 part of L-ascorbic acid and 1.418 parts of3-mercaptopropionic acid in 14.90 parts of deionized water was addeddropwise over 3.5 hours. Thereafter, the temperature was furthermaintained at 65° C. for 1 hour, and thereafter the polymerizationreaction was finished. The polymerizable component concentration (mass %concentration of all monomer components relative to all raw materials)at the time of finish of the polymerization reaction was 60%. Thereaction mixture was then neutralized to pH 7 with an aqueous solutionof sodium hydroxide at a temperature not higher than the polymerizationreaction temperature to give a polymer (C-2), corresponding to thepolymer (C) according to the present invention, composed of an aqueoussolution of the polymer having a weight average molecular weight of27,000. For the polymer obtained, the conversion (%) of each startingmonomer, the composition ratio of copolymer (% by mass), the compositionratio of copolymer (mole %), and the carboxylic acid content (meq/g)calculated on the unneutralized polymer basis are shown in Table 1.

Production Example 6

[0255] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 283 parts of deionized water, and 400 partsof unsaturated polyalkylene glycol ether derived from3-methyl-3-buten-1-ol by addition of 25 moles, on average, of ethyleneoxide. After raising the temperature to 65° C., an aqueous hydrogenperoxide solution composed of 0.519 part of hydrogen peroxide and 9.87parts of deionized water was added thereto. Then, 17.7 parts of acrylicacid and 39.3 parts of methoxytriethylene glycol monoacrylate were addeddropwise to the reaction vessel over 3 hours, and at the same time, anaqueous solution prepared by dissolving 0.672 part of L-ascorbic acidand 1.216 parts of 3-mercaptopropionic acid in 12.78 parts of deionizedwater was added dropwise over 3.5 hours. Thereafter, the temperature wasfurther maintained at 65° C. for 1 hour, and thereafter thepolymerization reaction was finished. The polymerizable componentconcentration (mass % concentration of all monomer components relativeto all raw materials) at the time of finish of the polymerizationreaction was 60%. The reaction mixture was then neutralized to pH 7 withan aqueous solution of sodium hydroxide at a temperature not higher thanthe polymerization reaction temperature to give a polymer (C-3),corresponding to the polymer (C) according to the present invention,composed of an aqueous solution of the polymer having a weight averagemolecular weight of 31,500. For the polymer obtained, the conversion (%)of each starting monomer, the composition ratio of copolymer (% bymass), the composition ratio of copolymer (mole %), and the carboxylicacid content (meq/g) calculated on the unneutralized polymer basis areshown in Table 1.

Production Example 7

[0256] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 285 parts of deionized water, and 400 partsof unsaturated polyalkylene glycol ether derived from methallyl alcoholby addition of 50 moles, on average, of ethylene oxide. After raisingthe temperature to 65° C., an aqueous hydrogen peroxide solutioncomposed of 0.530 part of hydrogen peroxide and 10.07 parts of deionizedwater was added thereto. Then, 16.0 parts of acrylic acid and 44.2 partsof 2-hydroxyethyl acrylate were added dropwise to the reaction vesselover 3 hours, and at the same time, an aqueous solution prepared bydissolving 0.687 part of L-ascorbic acid and 1.655 parts of3-mercaptopropionic acid in 13.05 parts of deionized water was addeddropwise over 3.5 hours. Thereafter, the temperature was furthermaintained at 65° C. for 1 hour, and thereafter the polymerizationreaction was finished. The polymerizable component concentration (mass %concentration of all monomer components relative to all raw materials)at the time of finish of the polymerization reaction was 60%. Thereaction mixture was then neutralized to pH 7 with an aqueous solutionof sodium hydroxide at a temperature not higher than the polymerizationreaction temperature to give a polymer (C-4), corresponding to thepolymer (C) according to the present invention, composed of an aqueoussolution of the polymer having a weight average molecular weight of31,000. For the polymer obtained, the conversion (%) of each startingmonomer, the composition ratio of copolymer (% by mass), the compositionratio of copolymer (mole %), and the carboxylic acid content (meq/g)calculated on the unneutralized polymer basis are shown in Table 1.

Production Example 8

[0257] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 218 parts of deionized water, and 400 partsof unsaturated polyalkylene glycol ether derived from allyl alcohol byaddition of 75 moles, on average, of ethylene oxide. After raising thetemperature to 80° C., an aqueous hydrogen peroxide solution composed of2.215 parts of hydrogen peroxide and 42.09 parts of deionized water wasadded thereto. Then, 14.6 parts of acrylic acid and 57.1 parts of2-hydroxyethyl acrylate were added dropwise to the reaction vessel over3 hours, and at the same time, an aqueous solution prepared bydissolving 2.869 parts of L-ascorbic acid and 0.864 part of3-mercaptopropionic acid in 54.51 parts of deionized water was addeddropwise over 3.5 hours. Thereafter, the temperature was furthermaintained at 80° C. for 1 hour, and thereafter the polymerizationreaction was finished. The polymerizable component concentration (mass %concentration of all monomer components relative to all raw materials)at the time of finish of the polymerization reaction was 60%. Thereaction mixture was then neutralized to pH 7 with an aqueous solutionof sodium hydroxide at a temperature not higher than the polymerizationreaction temperature to give a polymer (C-5), corresponding to thepolymer (C) according to the present invention, composed of an aqueoussolution of the polymer having a weight average molecular weight of32,000. For the polymer obtained, the conversion (%) of each startingmonomer, the composition ratio of copolymer (% by mass), the compositionratio of copolymer (mole %), and the carboxylic acid content (meq/g)calculated on the unneutralized polymer basis are shown in Table 1.

Production Example 9

[0258] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 1,698 parts of deionized water, and reactionvessel inside was purged with nitrogen with stirring, and then heated to80° C. in a nitrogen atmosphere. An aqueous solution of a monomermixture was prepared by mixing 1,848 parts of methoxypolyethylene glycolmonomethacrylate (mean number of moles of ethylene oxide added=25), 152parts of methacrylic acid, 500 parts of deionized water and furtheruniformly admixing therewith 11.9 parts of 3-mercaptopropionic acid as achain transfer agent. This aqueous monomer mixture solution and 184parts of a 10% aqueous solution of ammonium persulfate were respectivelyadded dropwise over 4 hours. After completion of the dropping, 46 partsof a 10% aqueous solution of ammonium persulfate was further addeddropwise over 1 hour. Thereafter, the temperature was further maintainedat 80° C. for 1 hour to drive the polymerization reaction to completion.The reaction mixture was then neutralized to pH 7 with an aqueoussolution of sodium hydroxide at a temperature not higher than thepolymerization reaction temperature to give a polymer (D-1),corresponding to the polymer (B3) according to the present invention,composed of an aqueous solution of the polymer having a weight averagemolecular weight of 31,000. For the polymer obtained, the conversion (%)of each starting monomer, the composition ratio of copolymer (% bymass), the composition ratio of copolymer (mole %), and the carboxylicacid content (meq/g) calculated on the unneutralized polymer basis areshown in Table 1.

Production Example 10

[0259] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 1,698 parts of deionized water, and reactionvessel inside was purged with nitrogen with stirring and then heated to80° C. in a nitrogen atmosphere. An aqueous solution of a monomermixture was prepared by mixing 1,796 parts of methoxypolyethylene glycolmonomethacrylate (mean number of moles of ethylene oxide added=25), 204parts of methacrylic acid, 500 parts of deionized water and furtheruniformly admixing therewith 17.6 parts of 3-mercaptopropionic acid as achain transfer agent. This aqueous monomer mixture solution and 184parts of a 10% aqueous solution of ammonium persulfate were respectivelyadded dropwise over 4 hours. After completion of the dropping, 46 partsof a 10% aqueous solution of ammonium persulfate was further addeddropwise over 1 hour. Thereafter, the temperature was further maintainedat 80° C. for 1 hour to drive the polymerization reaction to completion.The reaction mixture was then neutralized to pH 7 with an aqueoussolution of sodium hydroxide at a temperature not higher than thepolymerization reaction temperature to give a polymer (D-2),corresponding to the polymer (B3) according to the present invention,composed of an aqueous solution of the polymer having a weight averagemolecular weight of 28,000. For the polymer obtained, the conversion (%)of each starting monomer, the composition ratio of copolymer (% bymass), the composition ratio of copolymer (mole %), and the carboxylicacid content (meq/g) calculated on the unneutralized polymer basis areshown in Table 1.

Production Example 11

[0260] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 1,698 parts of deionized water, and reactionvessel inside was purged with nitrogen with stirring and then heated to80° C. in a nitrogen atmosphere. An aqueous solution of a monomermixture was prepared by mixing 1,668 parts of methoxypolyethylene glycolmonomethacrylate (mean number of moles of ethylene oxide added=25), 332parts of methacrylic acid, 500 parts of deionized water and furtheruniformly admixing therewith 16.7 parts of 3-mercaptopropionic acid as achain transfer agent. This aqueous monomer mixture solution and 184parts of a 10% aqueous solution of ammonium persulfate were respectivelyadded dropwise over 4 hours. After completion of the dropping, 46 partsof a 10% aqueous solution of ammonium persulfate was further addeddropwise over 1 hour. Thereafter, the temperature was further maintainedat 80° C. for 1 hour to drive the polymerization reaction to completion.The reaction mixture was then neutralized to pH 7 with an aqueoussolution of sodium hydroxide at a temperature not higher than thepolymerization reaction temperature to give a polymer (D-3),corresponding to the polymer (B3) according to the present invention,composed of an aqueous solution of the polymer having a weight averagemolecular weight of 24,000. For the polymer obtained, the conversion (%)of each starting monomer, the composition ratio of copolymer (% bymass), the composition ratio of copolymer (mole %), and the carboxylicacid content (meq/g) calculated on the unneutralized polymer basis areshown in Table 1.

Production Example 12

[0261] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 1,291 parts of deionized water, 1,812 partsof unsaturated polyalkylene glycol ether derived from3-methyl-3-buten-1-ol by addition of 50 moles, on average, of ethyleneoxide, and 188 parts of maleic acid. Reaction vessel inside was purgedwith nitrogen with stirring and then heated to 60° C. in a nitrogenatmosphere. Then, 50 parts of a 15% aqueous solution of NC-32W (productof Nippo Kagaku Corp., 2,2′-azobis-2-methylpropionamidine hydrochloride,purity 87%) was added. The temperature was maintained at 60° C. for 7hours and then raised to 80° C. and stirring was then continued for 1hour, and thereafter the polymerization reaction was finished. Thereaction mixture was then neutralized to pH 7 with an aqueous solutionof sodium hydroxide at a temperature not higher than the polymerizationreaction temperature to give a polymer (E-1), corresponding to thepolymer (B4) according to the present invention, composed of an aqueoussolution of the polymer having a weight average molecular weight of27,000. For the polymer obtained, the conversion (%) of each startingmonomer, the composition ratio of copolymer (% by mass), the compositionratio of copolymer (mole %), and the carboxylic acid content (meq/g)calculated on the unneutralized polymer basis are shown in Table 1.

Production Example 13

[0262] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 210 parts of deionized water and 386 parts ofunsaturated polyalkylene glycol ether derived from 3-methyl-3-buten-1-olby addition of 50 moles, on average, of ethylene oxide. After raisingthe temperature to 65° C., an aqueous hydrogen peroxide solutioncomposed of 1.33 parts of hydrogen peroxide and 65.17 parts of deionizedwater was added thereto. Then, 208 parts of 2-hydroxyethyl acrylate wasadded dropwise to the reaction vessel over 3 hours, and at the sametime, an aqueous solution prepared by dissolving 1.73 parts ofL-ascorbic acid and 4.16 parts of 3-mercaptopropionic acid in 114.11parts of deionized water was added dropwise over 3.5 hours. Thereafter,the temperature was further maintained at 65° C. for 1 hour, andthereafter the polymerization reaction was finished, to give a polymer(G-1), corresponding to the polymer (G) according to the presentinvention, composed of an aqueous solution of the polymer having aweight average molecular weight of 30,600. The polymerizable componentconcentration (mass % concentration of all monomer components relativeto all raw materials) at the time of finish of the polymerizationreaction was 60% and the acid value of the polymer was 0.04 (mg KOH/g).For the polymer obtained, the conversion (%) of each starting monomer,the composition ratio of copolymer (% by mass), the composition ratio ofcopolymer (mole %), and the carboxylic acid content (meq/g) calculatedon the unneutralized polymer basis are shown in Table 1.

Production Example 14

[0263] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 188 parts of deionized water and 386 parts ofunsaturated polyalkylene glycol ether derived from 3-methyl-3-buten-1-olby addition of 50 moles, on average, of ethylene oxide. After raisingthe temperature to 65° C., an aqueous hydrogen peroxide solutioncomposed of 1.76 parts of hydrogen peroxide and 86.24 parts of deionizedwater was added thereto. Then, 208 parts of methyl acrylate was addeddropwise to the reaction vessel over 3 hours, and at the same time, anaqueous solution prepared by dissolving 2.28 parts of L-ascorbic acidand 5.48 parts of 3-mercaptopropionic acid in 112.24 parts of deionizedwater was added dropwise over 3.5 hours. Thereafter, the temperature wasfurther maintained at 65° C. for 1 hour, and thereafter thepolymerization reaction was finished, to give a polymer (G-2),corresponding to the polymer (G) according to the present invention,composed of an aqueous solution of the polymer having a weight averagemolecular weight of 32,000. The polymerizable component concentration(mass % concentration of all monomer components relative to all rawmaterials) at the time of finish of the polymerization reaction was 60%and the acid value of the polymer was 0.04 (mg KOH/g). For the polymerobtained, the conversion (%) of each starting monomer, the compositionratio of copolymer (% by mass), the composition ratio of copolymer (mole%), and the carboxylic acid content (meq/g) calculated on theunneutralized polymer basis are shown in Table 1. TABLE 1 CompositionComposition Carboxylic acid Conversion (%) ratio of ratio of content(meq/g) of each starting copolymer (% copolymer calculated monomer bymass) (mole %) on the AO monomer/AA/ AO monomer/AA/ AO monomer/AA/unneutralized Polymer MAA/other MAA/other MAA/other basis A-194.0/97.8/0.0/0.0 83.5/16.5/0.0/0.0 17.2/82.8/0.0/0.0 1.83 A-292.5/98.0/0.0/0.0 84.2/15.8/0.0/0.0 18.1/81.9/0.0/0.0 1.74 A-352.0/97.0/0.0/0.0 82.8/17.2/0.0/0.0 11.9/88.1/0.0/0.0 1.90 C-181.3/99.7/0.0/HEA 99.8 83.9/5.9/0.0/HEA 10.1 32.0/28.6/0.0/HEA 39.4 0.64C-2 84.0/98.5/0.0/BA 100.0 84.4/5.7/0.0/BA 9.9 34.0/29.1/0.0/BA 36.90.62 C-3 85.5/98.8/0.0/MTA 100.0 84.6/5.7/0.0/MTA 9.7 34.4/29.0/0.0/MTA36.6 0.61 C-4 91.0/99.0/0.0/HEA 99.7 84.9/4.8/0.0/HEA 10.321.1/29.0/0.0/HEA 49.9 0.52 C-5 72.0/99.0/0.0/HEA 99.9 79.1/5.2/0.0/HEA15.7 11.0/25.8/0.0/HEA 63.2 0.56 D-1 100.0/0.0/100.0/0.090.6/0.0/9.4/0.0 46.5/0.0/53.4/0.0 0.89 D-2 100.0/0.0/100.0/0.087.5/0.0/12.5/0.0 38.7/0.0/61.3/0.0 1.19 D-3 100.0/0.0/100.0/0.080.0/0.0/20.0/0.0 26.5/0.0/73.5/0.0 1.93 E-1 90.0/0.0/0.0/MA 90.187.5/0.0/0.0/MA 12.5 32.7/0.0/0.0/MA 67.3 1.62 G-1 90.5/0.0/0.0/HEA100.0 62.7/0.0/0.0/HEA 37.3 7.9/0.0/0.0/HEA 92.1 0.0007 G-290.0/0.0/0.0/MEA 99.8 62.6/0.0/0.0/MEA 37.4 5.9/0.0/0.0/MEA 94.1 0.0007

[0264] In Table 1, the following abbreviations are used.

[0265] “AO monomer” stands for the unsaturated (poly)alkylene glycolether monomer (a) in polymers (A), (C), (E), and (G), and in polymer(D), it stands for the (poly)alkylene glycol mono(meth)acrylic acidester monomer (d). AA stands for acrylic acid, MAA for methacrylic acid,HEA for 2-hydroxyethyl acrylate, BA for butyl acrylate, MTA formethoxytriethylene glycol monoacrylate, MA for maleic acid, and MEA formethyl acrylate.

[0266] <Mortar Test>

[0267] Mortar compositions were prepared by using various cementadmixtures according to the present invention and various cementadmixtures for comparison. Each of them was prepared by combing theabove polymers, and subjected to mortar test. Each mortar test wascarried out in an atmosphere maintained at 25° C. using samplesconditioned at 25° C. The materials and mortar formulations used intesting were as follows.

[0268] (Formulation A) Ordinary portland cement produced by TaiheiyoCement 400 g, Toyoura standard sand 800 g, and deionized watercontaining a cement admixture according to the present invention or forcomparison 240 g (water/cement ratio (by mass)=0.60). For avoiding thepossible influence of bubbles in the mortar on the flowability of themortar, the air content was adjusted to 2.0±0.3% using a commercialoxyalkylene type antifoaming agent. The levels of addition of the cementadmixtures relative to cement (the amount of solid matter component[nonvolatile component] in cement admixture relative to cement) (% bymass) are shown in Table 2 and Table 4.

[0269] (Formulation B) Ordinary portland cement produced by TaiheiyoCement 800 g, Toyoura standard sand 400 g, and deionized watercontaining a cement admixture according to the present invention or forcomparison 205 g (water/cement ratio (by mass)=0.256). For avoiding thepossible influence of bubbles in the mortar on the flowability of themortar, the air content was adjusted to 2.0±0.3% using a commercialoxyalkylene type antifoaming agent. The levels of addition of the cementadmixtures relative to cement (the amount of solid matter component[nonvolatile component] in cement admixture relative to cement) (% bymass) are shown in Table 3.

[0270] (Mortar Flow Value Measurement) [Formulation A and Formulation B]

[0271] Each mortar composition was prepared by 30 seconds of dry mixing,at a low speed, of cement and sand alone using a HOBART-type mortarmixer (model N-50, product of HOBART Corp.), followed by addition of theabove cement admixture-containing deionized water, and 3 minutes ofkneading at a medium speed. The mortar obtained was filled into a hollowcylinder, 55 mm in inside diameter and in height, placed on a horizontaltable, to its highest level. Five minutes after start of kneading, thiscylinder was gently lifted up vertically, and the major axis and minoraxis of the mortar spread over the table were measured, and the meanvalue thereof was reported as mortar flow value. Thereafter, the wholeof the mortar was allowed to stand for a predetermined time in a tightlyclosed vessel, and the above procedure was repeated to thereby followthe change in mortar flow value with time. The results obtained areshown in Table 2 and Table 3. TABLE 2 Addition level Combination ratio(mass %)/cement (% by mass) Addition Flow value (mm) Formulation W/CFor- Polymer Polymer Polymer Polymer level after after after after ofmortar (%) mulation (A) (B) (A) (B) Total 5 min 30 min 60 min 90 minExample 1 Formulation A 60 A-1 + D-1 0.05 0.25 16.7% 83.3% 0.03 100 10098 86 Example 2 Formulation A 60 A-2 + D-1 0.05 0.25 16.7% 83.3% 0.03 99101 98 88 Example 3 Formulation A 60 A-3 + D-1 0.07 0.25 21.9% 78.1%0.32 97 94 96 88 Example 4 Formulation A 60 C-1 + A-1 0.35 0.05 87.5%12.5% 0.40 97 99 96 86 Example 5 Formulation A 60 C-2 + A-1 0.35 0.0587.5% 12.5% 0.40 98 97 95 89 Example 6 Formulation A 60 C-3 + A-1 0.350.05 87.5% 12.5% 0.40 100 102 99 91 Example 7 Formulation A 60 C-4 + A-10.35 0.05 87.5% 12.5% 0.40 98 100 98 88 Example 8 Formulation A 60 C-5 +A-1 0.45 0.05 90.0% 10.0% 0.50 96 95 92 85 Example 9 Formulation A 60C-1 + D-3 0.35 0.06 85.4% 14.6% 0.41 104 101 95 87 Example 10Formulation A 60 C-2 + D-3 0.35 0.06 85.4% 14.6% 0.41 102 100 97 90Example 11 Formulation A 60 C-4 + D-3 0.35 0.06 85.4% 14.6% 0.41 106 10398 89 Example 12 Formulation A 60 C-1 + E-1 0.35 0.08 81.4% 18.6% 0.4397 102 96 88 Example 13 Formulation A 60 C-2 + E-1 0.35 0.08 81.4% 18.6%0.43 97 95 92 87 Example 14 Formulation A 60 C-4 + E-1 0.35 0.08 81.4%18.6% 0.43 101 99 95 88 Compar.Ex.1 Formulation A 60 A-1 0.11 0.00 — —0.11 110 100 76 68 Compar.Ex.2 Formulation A 60 A-2 0.11 0.00 — — 0.11112 98 78 71 Compar.Ex.3 Formulation A 60 A-3 0.14 0.00 — — 0.14 109 9382 67 Compar.Ex.4 Formulation A 60 C-1 0.70 0.00 — — 0.70 88 93 89 83Compar.Ex.5 Formulation A 60 C-2 0.70 0.00 — — 0.70 86 86 85 82Compar.Ex.6 Formulation A 60 C-3 0.70 0.00 — — 0.70 89 92 89 84Compar.Ex.7 Formulation A 60 C-4 0.70 0.00 — — 0.70 87 90 88 83Compar.Ex.8 Formulation A 60 C-5 0.90 0.00 — — 0.90 85 84 82 79Compar.Ex.9 Formulation A 60 D-1 0.00 0.50 — — 0.50 87 83 83 81Compar.Ex.10 Formulation A 60 D-3 0.00 0.12 — — 0.12 118 107 87 72Compar.Ex.11 Formulation A 60 E-1 0.00 0.16 — — 0.16 105 106 90 70

[0272] TABLE 3 Addition level Combination ratio (mass %)/cement (% bymass) Addition Flow value (mm) Formuation W/C For- Polymer PolymerPolymer Polymer level after after after after of mortar (%) mulation (A)(B) (A) (B) Total 5 min 30 min 60 min 90 min Example 15 Formulation B25.6 A-1 + D-2 0.10 0.25 28.6% 71.4% 0.35 145 142 136 120 Example 16Formulation B 25.6 A-2 + D-2 0.10 0.25 28.6% 71.4% 0.35 155 154 141 119Example 17 Formulation B 25.6 A-3 + D-2 0.15 0.25 37.5% 62.5% 0.40 142139 133 123 Compar.Ex.12 Formulation B 25.6 A-1 0.20 0.00 — — 0.20 155134 106  94 Compar.Ex.13 Formulation B 25.6 A-2 0.20 0.00 — — 0.20 163151 120  88 Compar.Ex.14 Formulation B 25.6 A-3 0.30 0.00 — — 0.30 137125  91  71 Compar.Ex.15 Formulation B 25.6 D-2 0.00 0.50 — — 0.50 123135 130 131

[0273] Comments are made on Table 2 and Table 3 in the following. W/C(%) means the water/cement ratio (ratio by mass). The addition level(mass %)/cement refers to the level of addition of each cement admixturerelative to cement (the amount of solid matter component [nonvolatilecomponent] in cement admixture relative to cement) (% by mass).

[0274] As can be seen from Table 2 and Table 3, the polymers (A-1) to(A-3), (C-1) to (C-5), (D-1) to (D-3), and (E-1) when used alone, wereeither insufficient in dispersion retaining ability although theaddition level was low, or required markedly high addition levels formanifesting satisfactory levels of initial dispersing ability, However,in all of Examples 1 to 17 where these were used in combination,satisfactory levels of initial dispersing ability and of dispersionretaining ability were simultaneously attained at low addition levels.

[0275] (Formulation C)

[0276] Cement: Ordinary portland cement produced by Taiheiyo Cement 1000g

[0277] Fine aggregate: Mixed sand composed of Oi River system land sandand Kisarazu pit sand (specific gravity 2.62, FM 2.70)

[0278] Water: Deionized water containing a cement admixture according tothe present invention or for comparison (Water/cement ratio (bymass)=0.45, fine aggregate/cement ratio=2.5)

[0279] For avoiding the possible influence of bubbles in the mortar onthe flowability of the mortar, the air content was adjusted to 2.0±0.3%using a commercial oxyalkylene type antifoaming agent. The levels ofaddition of the cement admixtures relative to cement (the amount ofsolid matter component [nonvolatile component] in cement admixturerelative to cement) (% by mass) are shown in Table 5.

[0280] The solid matter component [nonvolatile component] in each cementadmixture was measured by drying an appropriate amount of the cementadmixture solution by heating at 130° C. to remove the volatile matter,and an amount of the aqueous admixture solution was weighed andincorporated in cement so that a predetermined amount of the solidmatter component [nonvolatile component] might be contained in theformulation.

[0281] (Mortar Flow Value Measurement) [Formulation C]

[0282] Each mortar composition was prepared using a HOBART-type mortarmixer (model N-50, product of HOBART Corp.). Cement and the cementadmixture-containing deionized water were added to the mixer, and after15 seconds of kneading at a low speed, the fine aggregate was added andthe mixture was kneaded for 60 seconds. That portion of mortar adheringto the mortar mixer vessel was scarped off and the whole mortar wasfurther kneaded for 4 minutes. The thus-prepared mortar was filled intoa flow cone (JIS R 5201) having an upper end inside diameter of 70 mm, alower end inside diameter of 100 mm and a height of 60 mm and placed ona horizontal flow table (JIS R 5201), to its highest level. Eightminutes after start of kneading, this flow cone was gently lifted upvertically. Then, after 15 times up and down movements caused byrevolving the handle once per second, the maximum diameter and thelength perpendicular thereto of the mortar spread over the table weremeasured, and the mean value thereof was reported as mortar flow value.Thereafter, the whole of the mortar was allowed to stand for apredetermined time in a tightly closed vessel, and the above procedurewas repeated to thereby follow the change in mortar flow value withtime. The results obtained are shown in Table 5. In the tables, thesymbol “−” given for flow value means that the initial mortal flow valuewas low and almost no flowing was observed, so that the change in mortalflow value with time was not checked. TABLE 4 Addition level Combinationratio (mass %)/cement (% by mass) Addition Flow value (mm) FormulationW/C For- Polymer Polymer Polymer Polymer level after after after afterof mortar (%) mulation (A) (B) (A) (B) Total 5 min 30 min 60 min 90 minExample 18 Formulation A 60 G-1 + D-3 0.05 0.12 29.4% 70.6% 0.17 122 125120 115 Example 19 Formulation A 60 G-2 + D-3 0.05 0.12 29.4% 70.6% 0.17117 121 114 109 Compar.Ex.16 Formulation A 60 G-1 1.00 0.00  100%  0.0%1.00  60 — — — Compar.Ex.17 Formulation A 60 G-2 1.00 0.00  100%  0.0%1.00  60 — — — Compar.Ex.10 Formulation A 60 D-3 0.00 0.12 — — 0.12 118107  87  72

[0283] TABLE 5 Addition level Combination ratio (mass %)/cement (% bymass) Addition Flow value (mm) Formulation W/C For- Polymer PolymerPolymer Polymer level after after after after of mortar (%) mulation (A)(B) (A) (B) Total 5 min 30 min 60 min 90 min Example 20 Formulation C 45G-1 + D-3 0.05 0.12 29.4% 70.6% 0.17 242 248 239 229 Example 21Formulation C 45 G-2 + D-3 0.05 0.12 29.4% 70.6% 0.17 232 239 230 217Compar.Ex.18 Formulation C 45 G-1 1.00 0.00  100%  0.0% 1.00 150 — — —Compar.Ex.19 Formulation C 45 G-2 1.00 0.00  100%  0.0% 1.00 150 — — —Compar.Ex.20 Formulation C 45 D-3 0.00 0.14 — — 0.14 241 207 196 182

[0284] As can be seen from Table 4 and Table 5, the polymers (G-1),(G-2), and (D-3), when used alone, were either insufficient indispersion retaining ability although the addition level was low, or nosatisfactory levels of initial dispersing ability was obtained even athigh addition levels. On the other hand, in all of Examples 20 and 21where these were used in combination, satisfactory levels of initialdispersing ability and of dispersion retaining ability weresimultaneously attained at low addition levels.

Production Example 15

[0285] A stainless-made high pressure reaction vessel equipped with athermometer, a stirrer, and a nitrogen and alkylene oxide inlet tube wascharged with 982 parts of methallyl alcohol as an unsaturated alcoholand 3.5 parts of sodium hydroxide as a catalyst for addition reaction.Reaction vessel inside was purged with nitrogen with stirring and thenheated to 150° C. in a nitrogen atmosphere. Then, under safe pressure,maintaining the temperature at 150° C., 6,279 parts of ethylene oxidewas introduced to the reaction vessel. The temperature was maintained at150° C. until the alkylene oxide addition reaction was completed todrive the reaction to completion. The obtained reaction product(hereinafter referred to as M-1) includes a non-polymerizablepolyalkylene glycol not containing an alkenyl group (polyethyleneglycol) as a by-product, and an unsaturated polyalkylene glycol ethermonomer (hereinafter referred to as MAL-10) derived from methallylalcohol by addition of 10 moles, on average, of ethylene oxide. Theproduction amount of polyethylene glycol was 4.0% relative to theunsaturated polyalkylene glycol ether monomer.

Production Example 16 to 21

[0286] The same procedure as in Production Example 15 was followedexcept that the species and used level of unsaturated alcohol andalkylene oxide, the used level of sodium hydroxide as the catalyst foraddition reaction, and the addition reaction temperature were changed asshown in Table 6, to perform alkylene oxide addition reaction to theunsaturated alcohol, to give reaction products (M-2) to (M-7) whichincluded an unsaturated polyalkylene glycol ether monomer and anon-polymerizable polyalkylene glycol not containing an alkenyl group.Furthermore, when two species of alkylene oxide, ethylene oxide andpropylene oxide were used, whole ethylene-oxide addition to unsaturatedalcohol was performed, then propylene oxide addition was performed toobtain block type adduct. The production amount of the polyalkyleneglycol as a by-product relative to the unsaturated polyalkylene glycolether monomer in obtained reaction product is shown in Table 6. TABLE 6Alkyl- Abbreviation Ethylene oxide Propylene oxide ene Sodium By-productof unsaturated Unsaturated alcohol Mean Mean oxide hydroxidepolyalkylene glycol Reaction polyalkylene Used Used number of Usednumber of addition Used Production Product glycol ether level levelmoles level moles temp. level amount No. monomer Species (parts) (parts)added (parts) added (° C.) (parts) Species (%) Pro- M-1 MAL-10 Methallyl982 6279 10 — — 150 3.5 Poly- 4.0 duction alcohol ethylene Ex.15 glycolPro- M-2 MAL-100 Methallyl 98 6390 100 — — 150 3.1 Poly- 6.4 ductionalcohol ethylene Ex.16 glycol Pro- M-3 IPN-25 3-methyl-3- 469 6336 25 —— 120 3.2 Poly- 5.2 duction buten-1-ol ethylene Ex.17 glycol Pro- M-4IPN-50 3-methyl-3- 234 6418 50 — — 120 3.1 Poly- 6.7 duction buten-1-olethylene Ex.18 glycol Pro- M-5 IPN-100 3-methyl-3- 117 6575 100 — — 1203.1 Poly- 9.4 duction buten-1-ol ethylene Ex.19 glycol Pro- M-6IPN-50EO3PO 3-methyl-3- 117 3228 50 250 3 120 1.7 Poly- 7.2 ductionbuten-1-ol ethylene Ex.20 poly- propyl- ene glycol Pro- M-7 AL-75 allyl105 6195 75 — — 150 3.1 Poly- 3.2 duction alcohol ethylene Ex.21 glycol

Production Example 22

[0287] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 270 parts of deionized water and 416.0 partsof the reaction product (M-1) obtained by Production Example 15(containing 400 parts of MAL-10 corresponding to unsaturatedpolyalkylene glycol ether monomer and 16.0 parts of polyethyleneglycol). Reaction vessel inside was purged with nitrogen with stirringand then heated to 65° C. in a nitrogen atmosphere. Then an aqueoushydrogen peroxide solution composed of 1.445 parts of hydrogen peroxideand 27.46 parts of deionized water was added thereto. Then, 96.8 partsof acrylic acid was added dropwise to the reaction vessel over 3 hours,and at the same time, an aqueous solution prepared by dissolving 1.871parts of L-ascorbic acid and 3.384 parts of 3-mercaptopropionic acid in35.56 parts of deionized water was added dropwise over 3.5 hours.Thereafter, the temperature was further maintained at 65° C. for 1 hour,and thereafter the polymerization reaction was finished. Thepolymerizable component concentration (mass % concentration of allmonomer components relative to all raw materials) at the time of finishof the polymerization reaction was 60%. The reaction solution was thenneutralized to pH 7 with an aqueous solution of sodium hydroxide at atemperature not higher than the polymerization reaction temperature togive a polymer (A-4), corresponding to the polymer (A) according to thepresent invention. For the polymer obtained, the conversion (%) of eachstarting monomer, and the analyzed results [the composition ratio ofcopolymer (% by mass), the composition ratio of copolymer (mole %), thecarboxylic acid content (meq/g) calculated on the unneutralized polymerbasis, the weight average molecular weight, the content (%) ofunsaturated polyalkylene glycol ether monomer (AO monomer) relative tothe neutralized polymer, and the content (%) of non-polymerizablepolyalkylene glycol not containing an alkenyl group relative to theneutralized polymer] of the polymer comprised in obtained polymersolution are shown in Table 8.

Production Example 23 to 26, Production Example 28 to 33

[0288] The same procedure as in Production Example 22 was followedexcept that the initial addition level of deionized water, the speciesand level of an unsaturated polyalkylene glycol ether monomer (includingthe by-product polyalkylene glycol), the level of hydrogen peroxide anddeionized water in hydrogen peroxide solution, the species and level ofunsaturated monocarboxylic acid monomer, the species and level ofunsaturated monocarboxylic acid ester monomer, the level of L-ascorbicacid, 3-mercaptopropionic acid, the level of deionized water used todissolve these, the component concentration of copolymer (mass %concentration of all monomer components relative to all raw materials),and the polymerization reaction temperature (the temperature of eachstage from after the addition of the initial addition component to theend of the polymerization reaction) were changed as shown in Table7.Polymers (A-5) to (A-8), (A-10), (A-11), corresponding to the polymer(A) according to the present invention, polymers (C-6) to (C-8),corresponding to the polymer (C) according to the present invention, anda polymer (G-3), corresponding to the polymer (G) according to thepresent invention were obtained. Further, the unsaturated monocarboxylicacid ester monomer was added dropwise over 3 hours with the unsaturatedmonocarboxylic acid monomer. For the polymer obtained, the conversion(%) of each starting monomer and the analyzed results of the polymercomprised in obtained polymer solution are shown in Table 8. Theabbreviations in Table 7 and Table 8 are same as shown in above Table 1.

Production Example 27

[0289] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 174 parts of deionized water. Reaction vesselinside was purged with nitrogen with stirring and then heated to 65° C.in a nitrogen atmosphere, an aqueous hydrogen peroxide solution composedof 0.630 part of hydrogen peroxide and 1.470 parts of deionized waterwas added thereto. An aqueous solution prepared by dissolving 426.8parts of the reaction product (M-4) obtained by Production Example 18(containing 400 parts of IPN-50 corresponding to unsaturatedpolyalkylene glycol ether monomer and 26.8 parts of polyethyleneglycol), 0.815 part of L-ascorbic acid, and 2.709 parts of 1-octanethiol in 100 parts of deionized water, and an aqueous solution preparedby dissolving 54.1 parts of acrylic acid in 29 parts of deionized waterwere respectively added dropwise over 3 hours thereto. Thereafter, thetemperature was further maintained at 65° C. for 1.5 hour, andthereafter the polymerization reaction was finished. The componentconcentration of copolymer (mass % concentration of all monomercomponents relative to all raw materials) at the time of finish of thepolymerization reaction was 60%. The reaction mixture was thenneutralized to pH 7 with an aqueous solution of sodium hydroxide at atemperature not higher than the polymerization reaction temperature togive a polymer (A-9), corresponding to the polymer (A) according to thepresent invention. For the polymer obtained, the conversion (%) of eachstarting monomer and the analyzed results of the polymer comprised inobtained polymer solution are shown in Table 8.

Production Example 34

[0290] A glass-made reaction vessel equipped with a thermometer, astirrer, a dropping funnel, a nitrogen inlet tube, and a refluxcondenser was charged with 279 parts of deionized water, 426.8 parts ofthe reaction product (M-4) obtained by Production Example 18 (containing400 parts of IPN-50 and 26.8 parts of polyethylene glycol), and 41.4parts of maleic acid. Reaction vessel inside was purged with nitrogenwith stirring and then heated to 65° C. in a nitrogen atmosphere. Anaqueous hydrogen peroxide solution composed of 0.362 part of hydrogenperoxide and 6.88 parts of deionized water was added thereto. Then, anaqueous solution prepared by dissolving 0.469 part of L-ascorbic acid in8.90 parts of deionized water was added dropwise over 1.5 hours.Thereafter, the temperature was further maintained at 65° C. for 1 hour,and thereafter the polymerization reaction was finished. The componentconcentration of copolymer (mass % concentration of all monomercomponents relative to all raw materials) at the time of finish of thepolymerization reaction was 60%. The reaction mixture was thenneutralized to pH 7 with an aqueous solution of sodium hydroxide at atemperature not higher than the polymerization reaction temperature togive a polymer (E-2), corresponding to the polymer (B4) according to thepresent invention. For the polymer obtained, the conversion (%) of eachstarting monomer and the analyzed results of the polymer comprised inobtained polymer solution are shown in Table 8. TABLE 7 Unsaturatedpolyalkylene glycol ether monomer Initial (including by-product additionUnsaturated polyalkylene glycol) level of Unsaturated monocarboxylicReaction deionized monocarboxylic acid ester Polymer ProductAbbreviation water acid monomer monomer No. No. of monomer Parts PartsSpecies Parts Species Parts Production A-4 M-1 MAL-10 416.0 270 AA 96.8— 0.0 Ex.22 Production A-5 M-2 MAL-100 425.6 276 AA 43.8 — 0.0 Ex.23Production A-6 M-3 IPN-25 420.8 268 AA 37.9 — 0.0 Ex.24 Production A-7M-5 IPN-100 437.6 270 AA 23.1 — 0.0 Ex.25 Production A-8 M-2 MAL-100425.6 269 AA 16.1 — 0.0 Ex.26 Production A-10 M-4 IPN-50 426.8 269 AA24.8 — 0.0 Ex.28 Production A-11 M-7 AL-75 412.8 168 AA 43.8 — 0.0 Ex.29Production C-6 M-4 IPN-50 426.8 275 AA 8.4 HEA 27.6 Ex.30 Production C-7IPN-50 426.8 291 AA 12.5 MTA 48.8 Ex.31 Production C-8 M-6 IPN-50EO3PO428.8 275 AA 8.4 HEA 27.6 Ex.32 Production G-3 M-4 IPN-50 426.8 353 AA0.0 HEA 215.4 Ex.33 3- Poly- Deionized L- mercapto Deionized merizableHydrogen water for ascorbic propionic water for component polymerizationperoxide dissolving acid acid dissolving conc. reaction temp. PartsParts Parts Parts Parts Mass % ° C. Production 1.445 27.46 1.871 3.38435.56 60 65 Ex.22 Production 0.474 9.01 0.614 1.851 11.67 60 65 Ex.23Production 0.587 11.51 0.760 1.833 14.44 60 65 Ex.24 Production 0.2785.29 0.361 0.869 6.85 60 65 Ex.25 Production 0.213 4.05 0.276 0.665 5.2460 65 Ex.26 Production 0.354 6.72 0.458 1.104 8.70 60 65 Ex.28Production 1.977 7.91 2.561 0.772 14.51 70 80 Ex.29 Production 0.3606.85 0.467 0.112 8.87 60 65 Ex.30 Production 0.389 7.39 0.504 0.304 9.5760 65 Ex.31 Production 0.352 6.69 0.456 0.110 8.66 60 65 Ex.32Production 1.382 26.25 1.789 4.313 34.00 60 65 Ex.33

[0291] TABLE 8 Conversion (%) Composition ratio Composition ratio ofeach starting of copolymer of copolymer Carboxylic acid Weight AOPolyalkylene monomer (% by mass) (mole %) content (meq/g) averagemonomer glycol AO monomer/ AO monomer/ AO monomer/ calculated on themolecular content content Polymer AA/MAA/other AA/MAA/other AA/MAA/otherunneutralized basis weight (%) (%) A-4 98.0/99.0/0.0/ 80.4/19.6/0.0/36.5/63.5/0.0/ 2.73 18500 1.6 3.1 0.0 0.0 0.0 A-5 94.3/96.8/0.0/89.9/10.1/0.0/ 12.5/87.5/0.0/ 1.40 54000 5.3 5.9 0.0 0.0 0.0 A-690.2/97.5/0.0/ 90.7/9.3/0.0/ 37.2/62.8/0.0/ 1.29 22500 9.6 5.1 0.0 0.00.0 A-7 82.0/94.6/0.0/ 93.8/6.2/0.0/ 19.4/80.6/0.0/ 0.87 49500 20.2 10.60.0 0.0 0.0 A-8 80.2/94.0/0.0/ 95.5/4.5/0.0/ 25.4/74.6/0.0/ 0.63 4800023.3 7.5 0.0 0.0 0.0 A-9 93.8/98.4/0.0/ 87.6/12.4/0.0/ 18.2/81.8/0.0/1.72 26000 5.6 6.0 0.0 0.0 0.0 A-10 84.0/97.2/0.0/ 93.3/6.7/0.0/30.5/69.5/0.0/ 0.93 27500 17.4 7.3 0.0 0.0 0.0 A-11 63.3/97.0/0.0/85.6/14.4/0.0/ 11.3/88.7/0.0/ 1.99 36500 47.6 4.2 0.0 0.0 0.0 C-686.0/98.0/0.0/ 90.6/2.2/0.0/ 29.9/22.8/0.0/ 0.30 101000 14.7 7.0 HEA99.8 HEA 7.2 HEA 47.3 C-7 91.7/99.0/0.0/ 85.7/2.9/0.0/ 28.9/30.8/0.0/0.40 98500 7.7 6.2 MTA 100.0 MTA 11.4 MTA 40.3 C-8 70.4/96.7/0.0/88.7/2.6/0.0/ 24.6/24.3/0.0/ 0.36 99000 37.0 9.0 HEA 99.6 HEA 8.7 HEA51.1 G-3 90.0/0.0/0.0/ 62.6/0.0/0.0/ 7.8/0.0/0.0/ 0.0007 32000 7.0 4.7HEA 100.0 HEA 37.4 HEA 92.2 E-2 88.5/0.0/0.0/ 90.8/0.0/0.0/33.3/0.0/0.0/ 1.59 26300 11.4 6.6 MA 87.0 MA 9.2 MA 66.7

[0292] In Table 8, AO monomer content (%) means the content (% by mass)of the unsaturated polyalkylene glycol ether monomer relative to theneutralized polymer, and polyalkylene glycol content (%) means thecontent (% by mass) of non-polymerizable polyalkylene glycol notcontaining an alkenyl group relative to the neutralized polymer.

[0293] <Mortar Test>

[0294] Mortar compositions were prepared by using various cementadmixtures according to the present invention and various cementadmixtures for comparison. Each of them was prepared by combing theabove polymers, and subjected to mortar test following the sameconditions described in above Formulation B. The levels of addition ofsolid matter component the cement admixtures relative to the cement (theamount of solid matter component [nonvolatile component] in each aqueoussolution of the polymer relative to the cement) (% by mass), the levelsof addition of each polymer (net amount) relative to the cement (% bymass), the total levels of addition of each polymer (net amount)relative to the cement (% by mass), the total levels of addition of AOmonomer relative to the total levels of addition of the polymer (netamount) (% by mass), the total levels of addition of the by-productpolyalkylene glycol relative to the total levels of addition of thepolymer (net amount) (% by mass), and the combination ratio of eachpolymer (net amount) (% by mass) are shown in Table 9 and Table 10.Further, above-mentioned ┌polymer (net amount)┘ corresponds to theamount of solid matter component [nonvolatile component] only of thepolymer. TABLE 9 Addition level of solid Addition level of Total mattercomponent polymer addition (mass %)/cement (net amount) level of PolymerPolymer (% by mass) polymer (A) (B) Polymer Polymer (net (solid (solid(A) (B) amount) Formulation W/C matter matter *net (net (mass %)/ ofmortar (%) Formulation component) component) amount) amount) cementExample 27 Formulation B 25.6 A-4 + A-5 0.20 0.12 0.191 0.108 0.299Example 23 Formulation B 25.6 A-6 + A-7 0.23 0.15 0.201 0.115 0.315Example 24 Formulation B 25.6 A-5 + A-8 0.12 0.24 0.108 0.184 0.291Example 25 Formulation B 25.6 A-9 + A-10 0.13 0.24 0.116 0.192 0.309Example 26 Formulation B 25.6 C-6 + A-9 0.20 0.18 0.164 0.161 0.326Example 27 Formulation B 25.6 C-7 + A-9 0.15 0.15 0.132 0.134 0.266Example 28 Formulation B 25.6 C-8 + A-9 0.22 0.18 0.151 0.161 0.312Example 29 Formulation B 25.6 G-3 + A-9 0.06 0.20 0.054 0.179 0.233Example 30 Formulation B 25.6 C-6 + A-11 0.20 0.28 0.164 0.185 0.349Example 31 Formulation B 25.6 C-7 + A-11 0.15 0.25 0.132 0.165 0.297Example 32 Formulation B 25.6 C-8 + A-11 0.22 0.28 0.151 0.185 0.336Example 33 Formulation B 25.6 G-3 + A-11 0.08 0.30 0.072 0.198 0.269Example 34 Formulation B 25.6 C-6 + D-3 0.20 0.16 0.164 0.160 0.324Example 35 Formulation B 25.6 C-7 + D-3 0.15 0.14 0.132 0.140 0.272Example 36 Formulation B 25.6 C-8 + D-3 0.22 0.16 0.151 0.160 0.311Example 37 Formulation B 25.6 G-3 + D-3 0.06 0.18 0.054 0.180 0.234Example 38 Formulation B 25.6 C-6 + E-2 0.15 0.23 0.123 0.195 0.318Example 39 Formulation B 25.6 C-7 + E-2 0.13 0.20 0.114 0.169 0.283Example 40 Formulation B 25.6 C-8 + E-2 0.15 0.23 0.103 0.195 0.298Example 41 Formulation B 25.6 G-3 + E-2 0.04 0.24 0.036 0.203 0.239Total addition Total addition level of AO level of Combination ratiomonomer polyalkylene of polymer Flow value (mm) (relative to glycol(relative (%) after after after after polymer % to polymer PolymerPolymer 5 30 60 90 by mass) % by mass) (A) (B) min min min min Example22 2.89 4.11 63.9 36.1 152 147 134 116 Example 23 13.45 7.07 63.6 36.4150 148 142 128 Example 24 16.60 6.92 37.0 63.0 148 144 134 115 Example25 12.95 6.47 37.7 62.3 146 145 135 116 Example 26 10.16 6.52 50.5 49.5141 160 155 146 Example 27 6.62 6.12 49.5 50.5 148 157 155 146 Example28 20.77 7.47 46.3 51.7 138 157 152 142 Example 29 5.89 5.71 23.1 76.9143 158 156 150 Example 30 32.06 5.50 47.1 52.9 138 159 152 137 Example31 29.85 5.06 46.0 54.0 145 152 148 140 Example 32 42.83 6.33 47.1 52.9135 156 148 134 Example 33 36.76 4.28 26.6 73.4 140 156 152 144 Example34 7.42 3.55 50.7 49.3 152 166 159 150 Example 35 3.73 3.01 48.5 51.5157 188 163 154 Example 36 17.96 4.37 48.5 51.5 148 162 156 145 Example37 1.60 1.07 23.0 77.0 150 161 160 155 Example 38 12.65 6.78 38.8 61.2138 157 153 148 Example 39 9.90 6.46 40.2 59.8 142 155 152 150 Example40 20.24 7.46 34.5 65.5 135 155 150 146 Example 41 10.73 6.34 15.0 85.0140 156 153 152

[0295] TABLE 10 Addition level of solid Addition level of Total mattercomponent polymer addition (mass %)/cement (net amount) level of Totaladdition Total addition Polymer Polymer (% by mass) polymer level of AOlevel of Combination ratio (A) (B) Polymer Polymer (net monomerpolyalkylene of polymer Flow value (mm) (solid (solid (A) (B) amount)(relative to glycol (relative (%) after after after after FormulationW/C matter matter (net (net (mass %)/ polymer % to polymer PolymerPolymer 5 30 60 90 of mortar (%) Formulation component) component)amount) amount) cement by mass) % by mass) (A) (B) min min min minCompar. Formulation B 25.6 A-4 0.60 — 0.573 — 0.573 1.55 3.09 100.0 —158 162 155 147 Ex.21 Compar. Formulation B 25.6 A-5 0.20 — 0.180 —0.180 5.27 5.92 100.0 — 166 148 120 88 Ex.22 Compar. Formulation B 25.6A-6 0.60 — 0.523 — 0.523 9.58 5.09 100.0 — 157 168 160 148 Ex.23 Compar.Formulation B 25.6 A-7 0.26 — 0.199 — 0.199 20.20 10.55 100.0 — 163 152135 110 Ex.24 Compar. Formulation B 25.6 A-8 0.80 — 0.612 — 0.612 23.257.52 100.0 — 153 162 156 140 Ex.25 Compar. Formulation B 25.6 A-9 0.22 —0.197 — 0.197 5.58 6.03 100.0 — 160 150 128 98 Ex.26 Compar. FormulationB 25.6 A-10 0.80 — 0.642 — 0.642 17.41 6.73 100.0 — 155 166 159 143Ex.27 Compar. Formulation B 25.6 A-11 0.32 — 0.211 — 0.211 47.57 4.15100.0 — 155 140 110 72 Ex.28 Compar. Formulation B 25.6 C-6 0.60 — 0.493— 0.493 14.65 7.01 100.0 — 85 177 174 165 Ex.29 Compar. Formulation B25.6 C-7 0.50 — 0.439 — 0.439 7.69 6.21 100.0 — 103 178 175 163 Ex.30Compar. Formulation B 25.6 C-8 0.60 — 0.411 — 0.411 37.03 9.01 100.0 —80 167 163 154 Ex.31 Compar. Formulation B 25.6 G-3 2.00 — 1.792 — 1.7926.95 4.66 100.0 — 60 — — — Ex.32 Compar. Formulation B 25.6 D-3 — 0.20 —0.200 0.200 0.00 0.00 — 100.0 168 154 133 102 Ex.33 Compar. FormulationB 25.6 E-2 — 0.25 — 0.212 0.212 11.39 6.64 — 100.0 152 148 132 105 Ex.34

[0296] As can be seen from Table 9 and Table 10, the polymers (A-4) to(A-11), (C-6) to (C-8), (G-3), (D-3), and (E-2) when used alone, wereeither insufficient in dispersion retaining ability although theaddition level was low, or required markedly high addition levels formanifesting satisfactory levels of initial dispersing ability, orinsufficient in initial dispersing ability although the addition levelwas high. However, in all of Examples 22 to 41 where these were used incombination, satisfactory levels of initial dispersing ability and ofdispersion retaining ability were simultaneously attained at lowaddition levels.

[0297] <Sulfonic Acid Type Dispersant (S)>

[0298] As a sulfonic acid type dispersant (S) containing a sulfonic acidgroup in the molecule, commercial items described below were used.

[0299] (S-1) Naphthalenesulfonic acid-formaldehyde condensates: Mighty150 (product of Kao Corp.)

[0300] (S-2) Ligninsulfonic acid salt: Pozzolith No. 8 (product ofPozzolith Bussan Corp.)

[0301] <Concrete Test>

[0302] (Preparation of Concrete Composition)

[0303] Concrete compositions were prepared by adding various cementadmixtures according to the present invention and various cementadmixtures for comparison. Each of them was prepared by using eachpolymer obtained by above Production Examples, and above sulfonic acidtype dispersants, and was subjected to concrete test. Two species ofconcrete compositions, composed of below-mentioned Formulation D andFormulation E, were prepared by using 3 types, which differed Lot number(X, Y, and Z), of Ordinary portland cement produced by Taiheiyo Cementas cement; Oi River system land sand as a fine aggregate; pit sandyielded Oume as a coarse aggregate; and tap water as mixing water.Further, in order temperature of the concrete composition to testtemperature, 20° C., the temperature of raw materials, therevolving-puddle mixer and the measurement equipments used for the testwas controlled under test temperature atmosphere, and mixing and eachmeasurement were performed under above-mentioned test temperatureatmosphere. Further, for avoiding the possible influence of bubbles inthe concrete composition on the flowability of the concrete composition,when necessary, the air content was adjusted to 1.0±0.3% using acommercial oxyalkylene type antifoaming agent.

[0304] (Formulation D) The cement: 320 kg/m³, water: 176 kg/m³, the fineaggregate: 822 kg/m³, the coarse aggregate: 892 kg/m³, the proportion ofthe fine aggregate (the fine aggregate/(the fine aggregate+the coarseaggregate)) (by volume): 48%, the ratio of water/cement (by mass)=0.55

[0305] (Formulation E) The cement: 473 kg/m³, water: 189 kg/m³, the fineaggregate: 722 kg/m³, the coarse aggregate: 884 kg/m³, the proportion ofthe fine aggregate (the fine aggregate/(the fine aggregate+the coarseaggregate)) (by volume): 45%, the ratio of water/cement (by mass)=0.40

[0306] The concrete was produced by 2 minutes mixing using therevolving-puddle mixer under above-mentioned condition, and the slumpvalue, the flow value, and the air content of the concrete weremeasured. The measurements of the slump value, the flow value, thechange in the slump value and the flow value by time, and the aircontent were performed following to Japanese Industrial Standards(JIS-A-1101 and 1128). When the comparison dispersing test with thecements of 3 types which differed Lot number (X, Y, and Z) wasperformed, in Formulation D, it compared at the addition level of thecement admixture where the slump value became 18.0 to 19.0 cm whencement X was used, and in Formulation E, it compared the addition levelof the cement admixture where the flow value became 600 to 650 mm whencement X was used. The solid matter component [nonvolatile component] ineach aqueous solution of the polymer obtained by above-mentionedProduction Examples and aqueous solution of above-mentioned sulfonicacid type dispersants was measured by weighing an appropriate amount ofeach solution, and drying by heating at 130° C. to remove the volatilematter, and an amount of the aqueous cement admixture solution wasweighed and incorporated in cement so that a predetermined amount of thesolid matter component [nonvolatile component] might be contained in theformulation. The results of the test and the addition level of thecement admixture relative to the cement are shown in Table 11 to Table14.

[0307] In Table 11 to 14, ┌polymer (A) or (G) (solid matter component)┘and ┌polymer (B) (solid matter component)┘ correspond to the amount ofsolid matter component [nonvolatile component] in each aqueous solutionof the polymer which includes the polymer, which includes thenonvolatile component not only the polymer but also other than thepolymer, e.g. the nonvolatile unreacted monomer and thenon-polymerizable polyalkylene glycol not containing an alkenyl group.

[0308] ┌polymer (A) or (G) (net amount)┘ and ┌polymer (B) (net amount)┘corresponds to the amount of solid matter component [nonvolatilecomponent] only of the polymer, ┌total┘ means the total of above┌polymer (A) of (G) (solid matter component)┘, ┌polymer (B) (solidmatter component)┘, and the amount of solid matter component in theaqueous solution of the sulfonic acid type dispersant. TABLE 11 Additionlevel of Addition level of solid matter component polymer (mass%)/cement (net amount) Polymer (% by mass)/cement (A) or (G) Polymer(B)Polymer (solid (solid Sulfonic (A) or (G) Polymer(B) Formulation mattermatter acid type (net (net of cencrete Formulation component) component)dispersant Total amount) amount) Example42 FormulationD A-8 + A-1 0.18 —0.12 0.30 0.138 — Example43 FormulationD C-6 + S-1 0.12 — 0.24 0.360.099 — Example44 FormulationD G-3 + S-1 0.10 — 0.27 0.37 0.090 —Example 45 FormulationD C-6 + A-9 + S-1 0.12 0.06 0.08 0.26 0.099 0.054Example46 FormulationD C-6 + E-2 + S-1 0.12 0.08 0.08 0.28 0.099 0.068Compar.EX.35 FormulationD A-8 0.40 — — 0.40 0.306 — Compar.EX.36FormulationD C-6 0.60 — — 0.60 0.493 — Compar.EX.37 FormulationD G-32.00 — — 2.00 1.792 — Compar.EX.38 FormulationD A-9 — 0.10 — 0.10 —0.090 Compar.EX.39 FormulationD E-2 — 0.13 — 0.13 — 0.110 Compar.EX.40FormulationD S-1 — — 0.30 0.30 — — Compar.EX.41 FormulationD S-2 — —0.35 0.35 — — Combination ratio (%) Polymer Slump value (cm) (A) or (G)Polymer(B) Sulfonic (cement X) (net (net acid type after after afteramount) amount) dispersant 5min 30min 60min Example42 53.4 0.0 46.6 18.817.0 14.3 Example43 29.1 0.0 70.9 18.5 20.2 15.5 Example44 24.9 0.0 75.118.2 21.3 18.2 Example45 42.5 23.1 34.4 18.5 20.4 17.0 Example46 40.027.5 32.5 18.2 20.8 17.5 Compar.EX.35 100.0 0.0 0.0 18.0 20.8 18.7Compar.EX.36 100.0 0.0 0.0 18.0 −(*1) −(*1) Compar.EX.37 100.0 0.0 0.0 2.0 −(*2) −(*2) Compar.EX.38 0.0 100.0 0.0 18.7 15.5 11.3 Compar.EX.390.0 100.0 0.0 18.8 16.0 12.5 Compar.EX.40 0.0 0.0 100.0 18.3 14.2  8.5Compar.EX.41 0.0 0.0 100.0 18.3 14.7 10.2

[0309] In Table 11, with the column of slump value, “−(*1)” means themeasurement was impossible because the slump value exceeded 25 cm, and“−(*2)” means the change in slump value by time was not measured becauseit was the state that the slump value was small and the concretecomposition did not flow almost. Addition level of Addition level ofsolid matter component polymer (mass %)/cement (net amount) Polymer (%by mass)/cement (A) or (G) Polymer(B) Polymer (solid (solid Sulfonic (A)or (G) Polymer(B) Formulation matter matter acid type (net (net ofconcrete Formulation component) component) dispersant Total amountamount) Example47 Formulation E C-6 + A-9 + S-2 0.16 0.07 0.25 0.480.132 0.63 Example48 Formulation E C-6 + E-2 + S-2 0.16 0.10 0.25 0.510.132 0.085 Compar.EX.42 Formulation E C-6 0.80 — — 0.80 0.658 —Compar.EX.43 Formulation E A-9 — 0.12 — 0.12 — 0.108 Compar.EX.44Formulation E E-2 — 0.16 — 0.16 — 0.136 Compar.EX.45 Formulation E S-1 —— 0.70 0.70 — — Compar.EX.46 Formulation E S-2 — — 1.00 1.00 — —Combination ratio (%) Flow value(mm) Polymer (cement X) (A) or (G)Polymer(B) Sulfonic (net (net acid type after after after amount)amount) dispersant 5min 30min 60min Example47 29.6 14.1 56.3 628 602 530Example48 28.2 18.2 53.6 613 605 557 Compar.EX.42 100.0 0.0 0.0 602−(*3) −(*3) Compar.EX.43 0.0 100.0 0.0 633 505 353 Compar.EX.44 0.0100.0 0.0 630 537 405 Comp.arEX.45 0.0 0.0 100.0 605 435 210Compar.EX.46 0.0 0.0 100.0 415 340 248

[0310] In Table 12, with the column of flow value, “−(*3)” means theflowability of the concrete composition increased considerably, materialseparation was caused, and the measurement of flow value was impossible.Addition level of Addition level of solid matter component polymer (mass%)/cement (net amount) Polymer (% by mass)/cement (A) or (G) Polymer(B)Polymer (solid (solid Sulfonic (A) or (G) Polymer(B) Formulation mattermatter acid type (net (net of concrete Formulation component) component)dispersant Total amount) amount) Example49 Formulation D A-10 + S-1 0.11— 0.08 0.19 0.088 — Example50 Formulation D A-11 + S-1 0.16 — 0.08 0.240.105 — Ref.Example1 Formulation D E-2 + S-1 — 0.13 0.08 0.21 — 0.110Example51 Formulation D A-10 + S-2 0.11 — 0.10 0.21 0.088 — Example52Formulation D A-11 + S-2 0.16 — 0.10 0.26 0.105 — Ref.Example2Formulation D E-2 + S-2 — 0.13 0.10 0.23 — 0.110 Example53 Formulation DC-6 + A-9 + S-2 0.12 0.06 0.10 0.28 0.099 0.054 Example54 Formulation DC-6 + E-2 + S-2 0.12 0.08 0.10 0.30 0.099 0.068 Compar.Ex.47 FormulationD A-10 0.14 — — 0.14 0.112 — Compar.Ex.48 Formulation D A-11 0.20 — —0.20 0.132 — Compar.Ex.49 Formulation D C-6 0.60 — — 0.60 0.493 —Compar.Ex.50 Formulation D A-9 — 0.10 — 0.10 — 0.090 Compar.Ex.51Formulation D E-2 — 0.13 — 0.13 — 0.110 Compar.Ex.52 Formulation D S-1 —— 0.30 0.30 — — Compar.Ex.53 Formulation D S-2 — — 0.35 0.35 — —Combination ratio (%) Polymer Slump value(cm) (A) or (G) Polymer(B)Sulfonic (net (net acid type cement cement cement amount) amount)dispersant X Y Z Example49 52.4 0.0 47.6 18.2 17.6 18.9 Example50 56.90.0 43.1 18.6 17.8 19.2 Ref.Example1 0.0 57.9 42.1 18.5 17.7 19.3Example51 46.9 0.0 53.1 18.4 17.8 19.0 Example52 51.3 0.0 48.7 18.5 17.919.1 Ref.Example2 0.0 52.4 47.6 18.7 18.0 19.5 Example53 39.1 21.3 39.618.3 17.5 19.2 Example54 37.0 25.5 37.5 18.2 17.4 19.0 Compar.Ex.47100.0 0.0 0.0 18.0 16.5 19.7 Compar.Ex.48 100.0 0.0 0.0 18.5 18.8 20.4Compar.Ex.49 100.0 0.0 0.0 18.0 16.2 19.5 Compar.Ex.50 0.0 100.0 0.018.7 16.8 20.8 Compar.Ex.51 0.0 100.0 0.0 18.8 17.0 20.7 Compar.Ex.520.0 0.0 100.0 18.3 18.1 18.5 Compar.Ex.53 0.0 0.0 100.0 18.3 18.0 18.5

[0311] Addition level of Addition level of solid matter componentpolymer (mass %)/cement (net amount) Polymer (% by mass)/cement (A) or(G) Polymer(B) Polymer (solid (solid Sulfonic (A) or (G) Polymer(B)Formulation matter matter acid type (net (net of concrete Formulationcomponent) component) dispersant Total amount) amount) Example55Formulation E A-10 + S-1 0.14 — 0.20 0.34 0.112 — Example56 FormulationE A-11 + S-1 0.20 — 0.20 0.40 0.132 — Example57 Formulation E C-6 +A-9 + S-2 0.16 0.07 0.25 0.48 0.132 0.063 Example58 Formulation E C-6 +E-2 + S-2 0.16 0.10 0.25 0.51 0.132 0.085 Compar.Ex.54 Formulation EA-10 0.18 — — 0.18 0.144 — Compar.Ex.55 Formulation E A-11 0.25 — — 0.250.165 — Compar.Ex.56 Formulation E C-6 0.80 — — 0.80 0.658 —Compar.Ex.57 Formulation E A-9 — 0.12 — 0.12 — 0.108 Compar.Ex.58Formulation E E-2 — 0.16 — 0.16 — 0.136 Compar.Ex.59 Formulation E S-1 —— 0.70 0.70 — — Compar.Ex.60 Formulation E S-2 — — 1.00 1.00 — —Combination ratio (%) Polymer Slump value(cm) (A) or (G) Polymer(B)Sulfonic (net (net acid type cement cement cement amount) amount)dispersant X Y Z Example55 36.0 0.0 64.0 15 580 653 Example56 39.7 0.060.3 620 577 660 Example57 29.6 14.1 56.3 628 582 676 Example58 28.218.2 53.6 613 575 655 Compar.Ex.54 100.0 0.0 0.0 617 520 715Compar.Ex.55 100.0 0.0 0.0 620 512 728 Compar.Ex.56 100.0 0.0 0.0 602508 692 Compar.Ex.57 0.0 100.0 0.0 633 515 747 Compar.Ex.58 0.0 100.00.0 630 563 728 Compar.Ex.59 0.0 0.0 100.0 605 593 618 Compar.Ex.60 0.00.0 100.0 415 410 422

[0312] As can be seen from Table 11 and Table 12, the polymers (A-8),(A-9), (C-6), (G-3), and (E-2) when used alone, were either insufficientin dispersion retaining ability although the addition level was low, orrequired markedly high addition levels for manifesting satisfactorylevels of initial dispersing ability, or insufficient in initialdispersing ability although the addition level was high. On the otherhand, the dispersants (S-1) or (S-2) correspond to the sulfonic acidtype dispersant (S) containing a sulfonic acid group in the molecule,when used alone, the change in the slump value or the flow value by timewas large, and insufficient in dispersion retaining ability. However,all of Examples 42 to 48 where above polymers and the sulfonic acid typedispersant were used in combination, satisfactory levels of initialdispersing ability and of dispersion retaining ability weresimultaneously attained at low addition levels.

[0313] As can be seen from Table 13 and Table 14, for the polymers(A-10), (A-11), (C-6), (A-9), and (E-2) when used alone, either thevariance of the dispersing ability caused by cement Lot No. was largealthough the addition level was low, or required markedly high additionlevels for manifesting satisfactory levels of initial dispersingability. On the other hand, for the dispersants (S-1) or (S-2)correspond to the sulfonic acid type dispersant (S) containing asulfonic acid group in the molecule, when used alone, although thevariance of dispersing ability caused by cement Lot No. was small, whenwater/cement ratio became low, the addition level necessary fordispersion suddenly increased. However, all of Examples 49 to 58 whereabove polymers and the sulfonic acid type dispersant were used incombination, satisfactory levels of dispersing ability were attained atlow addition levels, and the variance of dispersing ability caused bycement Lot No. was small, in addition, the stabilized dispersing abilitywas able to be obtained.

INDUSTRIAL APPLICABILITY

[0314] The cement admixture of the present invention shows high levelsof dispersing ability at low addition levels and, in particular, it canmanifest excellent initial dispersing ability and dispersion retainingability in a high water reducing ratio range. The cement compositionwith the cement admixture of the present invention incorporated thereinshows good flowability and can avoid troubles otherwise encountered inconstruction works.

1. A cement admixture comprising two polymers, namely a polymer (A1) anda polymer (B1), as essential constituents in a ratio of polymer (A1) topolymer (B1) between 1 to 99/99 to 1% by mass, wherein the polymer (A1)is a polymer comprising, as essential constituent units, a constituentunit (I) derived from an unsaturated (poly)alkylene glycol ether monomer(a1) represented by the general formula (1): YO(R¹O)_(m)H  (1) wherein Yrepresents an alkenyl group containing 2 to 8 carbon atoms, the m R¹Ogroups are the same or different and each R¹O represents an oxyalkylenegroup containing 2 to 18 carbon atoms and m is a mean addition number ofmoles of the oxyalkylene group and represents a number of 1 to 500, anda constituent unit (II) derived from an unsaturated monocarboxylic acidmonomer (b) and wherein the constituent units (I) and (II) each accountsfor not less than 1% by mass relative to all constituent units but theconstituent unit (I) accounts for not more than 50 mole percent relativeto all constituent units and, wherein the polymer (B1) is an oxyalkylenegroup- or polyoxyalkylene group- and carboxyl group-containing polymer:2. A cement admixture comprising two polymers, namely a polymer (A2) anda polymer (B2), as essential constituents in a ratio of polymer (A2) topolymer (B2) between 1 to 99/99 to 1% by mass, wherein the polymer (A2)is a polymer comprising, as essential constituent units, a constituentunit (I′) derived from an unsaturated (poly)alkylene glycol ethermonomer (a2) represented by the general formula (2): YO(R¹O)_(n)R²  (2)wherein Y represents an alkenyl group containing 2 to 8 carbon atoms,the n R¹O groups are the same or different and each R¹O represents anoxyalkylene group containing 2 to 18 carbon atoms, R² represents ahydrogen atom or a hydrocarbon group containing 1 to 30 carbon atoms andn is a mean addition number of moles of the oxyalkylene group andrepresents a number of 1 to 500, a constituent unit (II) derived from anunsaturated monocarboxylic acid monomer (b) and a constituent unit (III)derived from an unsaturated monocarboxylic ester monomer (c), whereinthe constituent units (I′), (II) and (III) each accounts for not lessthan 1% by mass relative to all constituent units but the constituentunit (I′) accounts for not more than 50 mole percent relative to allconstituent units and the sum of the proportions of the constituentunits (II) and (III) is greater than the proportion of the constituentunit (I′) on the mole ratio basis, wherein the polymer (B2) is anoxyalkylene group- or polyoxyalkylene group- and carboxylgroup-containing polymer.
 3. The cement admixture according to claim 2,wherein the constituent unit (III) derived from an unsaturatedmonocarboxylic acid ester monomer (c) is a constituent unit (IV) derivedfrom a (poly)alkylene glycol mono(meth)acrylic acid ester monomer (d)represented by the general formula (3):

wherein R³ and R⁴ are the same or different and each represents ahydrogen atom or a methyl group, the p R⁵O groups are the same ordifferent and each R⁵O represent an oxyalkylene group containing 2 to 18carbon atoms, p is a mean addition number of moles of the oxyalkylenegroup and represents a number of 1 to 500, and R represents a hydrogenatom or a hydrocarbon group containing 1 to 30 carbon atoms, or aconstituent unit (VI) derived from a hydrophobic unsaturatedmonocarboxylic acid ester monomer (f) represented by the general formula(4):

wherein R⁷ and R⁸ are the same or different and each represents ahydrogen atom or a methyl group and R⁹ represents a hydrocarbon groupcontaining 1 to 30 carbon atoms.
 4. A cement admixture comprising twopolymers, namely a polymer (A3) and a polymer (B3), as essentialconstituents in a ratio of polymer (A3) to polymer (B3) between 1 to99/99 to 1% by mass, wherein the polymer (A3) is a polymer comprising,as essential constituent units, a constituent unit (I′) derived from anunsaturated (poly)alkylene glycol ether monomer (a2) represented by thegeneral formula (2): YO(R¹O)_(n)R²  (2) wherein Y represents an alkenylgroup containing 2 to 8 carbon atoms, the n R¹O groups are the same ordifferent and each R¹O represents an oxyalkylene group containing 2 to18 carbon atoms, R² represents a hydrogen atom or a hydrocarbon groupcontaining 1 to 30 carbon atoms and n is a mean addition number of molesof the oxyalkylene group and represents a number of 1 to 500, and aconstituent unit (II) derived from an unsaturated monocarboxylic acidmonomer (b) and wherein the constituent units (I′) and (II) eachaccounts for not less than 1% by mass relative to all constituent unitsbut the constituent unit (I′) accounts for not more than 50 mole percentrelative to all constituent units and wherein the polymer (B3) is apolymer comprising a constituent unit (IV) derived from a (poly)alkyleneglycol mono(meth)acrylic acid ester monomer (d) represented by thegeneral formula (3):

wherein R³ and R⁴ are the same or different and each represents ahydrogen atom or a methyl group, the p R⁵O groups are the same ordifferent and each R⁵O represent an oxyalkylene group containing 2 to 18carbon atoms, p is a mean addition number of moles of the oxyalkylenegroup and represents a number of 1 to 500, and R⁶ represents a hydrogenatom or a hydrocarbon group containing 1 to 30 carbon atoms, and aconstituent unit (II) derived from an unsaturated monocarboxylic acidmonomer (b).
 5. A cement admixture comprising two polymers, namely apolymer (A3) and a polymer (B4), as essential constituents in a ratio ofpolymer (A3) to polymer (B4) between 1 to 99/99 to 1% by mass, whereinthe polymer (A3) is a polymer comprising, as essential constituentunits, a constituent unit (I′) derived from an unsaturated(poly)alkylene glycol ether monomer (a2) represented by the generalformula (2): YO(R¹O)_(n)R²  (2) wherein Y represents an alkenyl groupcontaining 2 to 8 carbon atoms, the n R¹O groups are the same ordifferent and each R¹O represents an oxyalkylene group containing 2 to18 carbon atoms, R² represents a hydrogen atom or a hydrocarbon groupcontaining 1 to 30 carbon atoms and n is a mean addition number of molesof the oxyalkylene group and represents a number of 1 to 500, and aconstituent unit (II) derived from an unsaturated monocarboxylic acidmonomer (b), wherein the constituent units (I′) and (II) each accountsfor not less than 1% by mass relative to all constituent units but theconstituent unit (I′) accounts for not more than 50 mole percentrelative to all constituent units, wherein the polymer (B4) is a polymercomprising a constituent unit (I′) derived from an unsaturated(poly)alkylene glycol ether monomer (a2) represented by the generalformula (2) and a constituent unit (V) derived from an unsaturateddicarboxylic acid monomer (e).
 6. A cement admixture comprising twopolymers, namely a polymer (G) and a polymer (B5), as essentialconstituents in a ratio of polymer (G) to polymer (B5) between 1 to99/99 to 1% by mass, wherein the polymer (B5) is an oxyalkylene orpolyoxyalkylene group- and carboxyl group-containing polymer and thepolymer (G) is a polymer comprising, as essential constituent units, aconstituent unit (I′) derived from an unsaturated (poly)alkylene glycolether monomer (a2) represented by the general formula (2):YO(R¹O)_(n)R²  (2) wherein Y represents an alkenyl group containing 2 to8 carbon atoms, the n R¹O groups are the same or different and each R¹Orepresents an oxyalkylene group containing 2 to 18 carbon atoms, R²represents a hydrogen atom or a hydrocarbon group containing 1 to 30carbon atoms and n is the mean addition number of moles of theoxyalkylene group and represents a number of 1 to 500, and a constituentunit (III) derived from an unsaturated monocarboxylic acid ester monomer(c), wherein the constituent units (I′) and (III) each accounts for notless than 1% by mass relative to all constituent units but theconstituent unit (I′) accounts for not more than 50 mole percentrelative to all constituent units.
 7. The cement admixture according toclaim 6, wherein the number of milliequivalents of carboxyl groupscontained in each gram of the polymer (G) as determined on theunneutralized basis is 0 to 0.8 meq/g.
 8. The cement admixture accordingto claim 6 or 7, wherein the polymer (B5) is a polymer comprising, asessential constituent units, a constituent unit (IV) derived from a(poly)alkylene glycol mono(meth)acrylic acid ester monomer (d)represented by the general formula (3):

wherein R³ and R⁴ are the same or different and each represents ahydrogen atom or a methyl group, the p R⁵O groups are the same ordifferent and each R⁵O represent an oxyalkylene group containing 2 to 18carbon atoms, p is a mean addition number of moles of the oxyalkylenegroup and represents a number of 1 to 500 and R⁶ represents a hydrogenatom or a hydrocarbon group containing 1 to 30 carbon atoms, and aconstituent unit (II)derived from an unsaturated monocarboxylic acidmonomer (b).
 9. The cement admixture according to claim 6 or 7, whereinthe polymer (B5) is a polymer comprising, as essential constituentunits, the constituent unit (I′) derived from an unsaturated(poly)alkylene glycol ether monomer (a2) represented by the generalformula (2) and a constituent unit (V) derived from an unsaturateddicarboxylic acid monomer (e).
 10. The cement admixture according to anyof claims 6 to 9, wherein the constituent unit (III) derived from anunsaturated monocarboxylic acid ester monomer (c) is a constituent unit(IV) derived from a (poly)alkylene glycol mono(meth)acrylic acid estermonomer (d) or a constituent unit (VI) derived from a hydrophobicunsaturated monocarboxylic acid ester monomer (f) represented by thegeneral formula (4):

wherein R⁷ and R⁸ are the same or different and each represents ahydrogen atom or a methyl group and R⁹ represents a hydrocarbon groupcontaining 1 to 30 carbon atoms.
 11. The cement admixture according toany of claims 1 to 10 comprising a non-polymerizable (poly)alkyleneglycol (P) not containing an alkenyl group.
 12. The cement admixtureaccording to claim 1 comprising the unsaturated (poly)alkylene glycolether monomer (a1).
 13. The cement admixture according to any of claims2 to 11 comprising the unsaturated (poly)alkylene glycol ether monomer(a2).
 14. A cement composition comprising, as essential constituents,the cement admixture according to any of claims 1 to 13, cement andwater.